Differential utilization of thyroid lobectomy after the 2015 American Thyroid Association guideline update

in Endocrine Oncology
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Patricia Gina Lu Department of General Surgery, Division of Surgical Oncology and Endocrine Surgery, Mayo Clinic in Arizona, Phoenix, Arizona, USA

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Zhi Ven Fong Department of General Surgery, Division of Surgical Oncology and Endocrine Surgery, Mayo Clinic in Arizona, Phoenix, Arizona, USA

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Patrick T Hangge Department of General Surgery, Division of Surgical Oncology and Endocrine Surgery, Mayo Clinic in Arizona, Phoenix, Arizona, USA

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Yu-Hui Chang Department of Quantitative Health Sciences, Mayo Clinic in Arizona, Scottsdale, Arizona, USA

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Elisabeth S Lim Department of Quantitative Health Sciences, Mayo Clinic in Arizona, Scottsdale, Arizona, USA

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Nabil Wasif Department of General Surgery, Division of Surgical Oncology and Endocrine Surgery, Mayo Clinic in Arizona, Phoenix, Arizona, USA

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Patricia A Cronin Department of General Surgery, Division of Surgical Oncology and Endocrine Surgery, Mayo Clinic in Arizona, Phoenix, Arizona, USA

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Chee-Chee Stucky Department of General Surgery, Division of Surgical Oncology and Endocrine Surgery, Mayo Clinic in Arizona, Phoenix, Arizona, USA

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Correspondence should be addressed to P G Lu: Lu.patricia@mayo.edu
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Background

The 2015 American Thyroid Association (ATA) guidelines added thyroid lobectomy (TL) as the appropriate treatment for low-risk differentiated thyroid cancer (DTC). We aimed to investigate the population-level factors that influence the utilization of TL.

Methods

The Surveillance, Epidemiology and End Results (SEER) database was queried for all DTC patients fitting low-risk criteria as defined by the ATA. Trends in total thyroidectomy (TT) and TL were identified using a Cochrane–Armitage test. Multivariable logistic regression identified patient and socioeconomic characteristics associated with TL, and difference-in-difference analysis was used to control for secular trends over time.

Results

A total of 43,526 patients with low-risk DTC were identified in the SEER database; 39,411 pre-2015 and 4115 post-2015. After 2015, TT continued to outnumber TL (76.2% vs 23.8%), although the rate of TL increased significantly (11.6% to 23.8%, P < 0.001). However, difference-in-difference analysis found that age > 55 (OR 1.11, 95% CI 1.01–1.19, P < 0.001) and rurality (OR 1.16, 95% CI 1.05–1.28, P < 0.001) were independently associated with TT. TL was associated with T1 disease (OR 1.11, 95% CI 1.04–1.19, P = 0.001).

Conclusion

Although the 2015 ATA guideline update led to an increase in TL for low-risk DTC, most patients still underwent TT. Age and neighborhood significantly impact the odds of receiving guideline-appropriate TL for low-risk DTC, especially for T2 disease.

Abstract

Background

The 2015 American Thyroid Association (ATA) guidelines added thyroid lobectomy (TL) as the appropriate treatment for low-risk differentiated thyroid cancer (DTC). We aimed to investigate the population-level factors that influence the utilization of TL.

Methods

The Surveillance, Epidemiology and End Results (SEER) database was queried for all DTC patients fitting low-risk criteria as defined by the ATA. Trends in total thyroidectomy (TT) and TL were identified using a Cochrane–Armitage test. Multivariable logistic regression identified patient and socioeconomic characteristics associated with TL, and difference-in-difference analysis was used to control for secular trends over time.

Results

A total of 43,526 patients with low-risk DTC were identified in the SEER database; 39,411 pre-2015 and 4115 post-2015. After 2015, TT continued to outnumber TL (76.2% vs 23.8%), although the rate of TL increased significantly (11.6% to 23.8%, P < 0.001). However, difference-in-difference analysis found that age > 55 (OR 1.11, 95% CI 1.01–1.19, P < 0.001) and rurality (OR 1.16, 95% CI 1.05–1.28, P < 0.001) were independently associated with TT. TL was associated with T1 disease (OR 1.11, 95% CI 1.04–1.19, P = 0.001).

Conclusion

Although the 2015 ATA guideline update led to an increase in TL for low-risk DTC, most patients still underwent TT. Age and neighborhood significantly impact the odds of receiving guideline-appropriate TL for low-risk DTC, especially for T2 disease.

Introduction

In October 2015, the American Thyroid Association (ATA) updated their guidelines on the treatment of differentiated thyroid cancer (DTC) with the strong recommendation that DTC < 4 cm without extrathyroidal extension or clinical lymph node involvement may be sufficiently treated by thyroid lobectomy (TL) alone (Haugen et al. 2016). This was in response to more recent data showing that for properly selected patients, there was no significant difference in survival after TL versus total thyroidectomy (TT) (Haigh et al. 2005, Mendelsohn et al. 2010, Barney et al. 2011, Matsuzu et al. 2014), and adjuvant radioactive iodine therapy after TT does not improve overall or disease-free survival (Schvartz et al. 2012). For example, Barney et al. found that of 23,605 patients diagnosed with DTC between 1983 and 2002 undergoing TT vs TL, there was no difference in 10-year overall survival or 10-year disease-specific survival (Barney et al. 2011). This was also demonstrated by Nixon et al., who not only found no difference in 10-year overall or disease-specific survival but also no significant difference in local or regional recurrence (Nixon et al. 2012).

This change in national guidelines matters because multiple studies have shown that TL is associated with lower rates of complications, specifically lower rates of temporary vocal cord paralysis, temporary hypoparathyroidism, and permanent hypoparathyroidism (Chun et al. 2015, Gunn et al. 2020, Hsiao et al. 2022). A review of the National Surgical Quality Improvement Program database from 2016 to 2017 found that TT was an independent risk factor for recurrent laryngeal nerve injury (Gunn et al. 2020). In addition, after TL, patients may not require lifelong thyroid hormone replacement or may only require lower doses with quicker adjustment to euthyroidism, which has been proven to significantly improve quality of life (Kluijfhout et al. 2016).

Multiple studies have since demonstrated that the utilization of TL for low-risk DTC has risen after 2015, although it is still outnumbered by TT (Ullmann et al. 2019, Toumi et al. 2021). Gordon et al. found that it was primarily academic institutions that were adopting TL, suggesting there was still room for growth at the community level (Gordon et al. 2022). Meanwhile, Collins et al. found that the guidelines changed practice patterns toward TL in both urban and rural settings (Collins et al. 2023). Given variable findings in the current literature, we sought to perform a thorough investigation of a multitude of factors to determine what influences the uptake of TL for low-risk DTC at the population level.

Materials and methods

Data source

The SEER database comprises cancer incidence data from population-based cancer registries covering approximately 48% of the U.S. population. Unlike other cancer registries, the SEER database is not affiliated with specific hospitals or accredited programs. The registries collect data on patient demographics, primary tumor site, morphology, stage at diagnosis, first course of treatment, and follow-up for mortality statistics. The data are de-identified; thus, informed consent is not obtained. Of note, SEER collects data based on the North American Association of Central Cancer Registries’ Data Standards. Patient race and ethnicity data are pulled directly from the medical record. The research database contains data from 1975 to 2019 and is accessible to the public.

Study population

The SEER database was queried for all thyroid cancer patients who underwent thyroid lobectomy or thyroidectomy between 2004 and 2018. This was identified using the following ICD-0-3 histology codes: 8050, 8260, 8330, 8331, 8332, 8335, 8339, 8340, 8342, 8343, 8344 with the primary site as c73.9-Thyroid gland. Patients with medullary or undifferentiated thyroid cancer, tumor <1 cm or >4 cm, locally advanced disease, or clinical lymph node involvement were excluded. Therefore, only patients diagnosed with papillary or follicular thyroid carcinoma meeting the low-risk criteria defined in the guideline update were included.

Covariates

Patient-level characteristics at the time of surgery were collected, including demographics, household income, and residence in a metropolitan area. Tumor characteristics were also collected, including tumor histology, pathologic lymph node status, and pathologic T stage. Pathologic lymph node status was stratified by SEER into negative nodes, positive nodes, no nodes examined, and not reported. Pathologic T stage was used because patients’ clinical T stage was not available in SEER for most of the study period. The study period was stratified into two groups: patients undergoing surgery between 2004 and 2015 (pre-2015) and those undergoing surgery between 2016 and 2018 (post-2015). Within the two groups, the data were also stratified by surgical approach (TL vs TT).

Statistical analysis

The analysis was conducted using SAS 9.4 (SAS Institute) and R 4.2.1 (R Foundation for Statistical Computing). Descriptive statistics were used to summarize the data. Patient demographic and tumor characteristics of the pre-2015 and post-2015 cohorts were compared by the Wilcoxon rank sum test for continuous variables or the Chi-square test for categorical variables. The Cochran–Armitage test was used to assess the temporal trend of TT and TL. Multivariable logistic regression was used to model the probability of guideline compliance while accounting for measured confounders; study group (pre- and post-2015), age, sex, race, urban or rural residence, T stage, nodal status, and the two-way interactions of group with all the other covariates were included in the model. Household income was not included in the multivariable analysis as it was found to be collinear with living in a metropolitan area. The measure of the association between a covariate and guideline compliance was quantified by the odds ratio (OR) with a 95% confidence interval (CI) for each study group. Difference-in-difference analysis, a method of comparing changes in outcomes across an intervention by subtracting one from the other to control for confounding secular trends over time, was also performed. The results were then presented as a plot of the adjusted probability of guideline compliance by each covariate over time. The influence of secular change was assessed by the Wald test for the interaction term. All tests were two-sided and a P-value < 0.05 was considered statistically significant.

Results

Demographics

A total of 46,116 patients with low-risk, well-differentiated thyroid cancer were identified. Of these, 39,130 were treated before 2015 and 6986 after. Compared to those who were treated after, those treated before 2015 were younger (age over 55, 32.7% vs 36.9%, P < 0.001), more likely to be White (81.7% vs 80.7%, P = 0.048), non-Hispanic (14.0% vs 17.5%, P < 0.001), and less likely to have a median household income >$50,000 (87.8% vs 89.5%, P < 0.001) (Table 1). Tumor characteristics were also significantly different between these two cohorts, with more follicular carcinoma in the pre-2015 cohort (9% vs 7.1%, P = 0.049) and more T1 tumors in the post-2015 cohort (64.1% vs 62.1%, P = 0.002). In terms of lymph node status, both groups had over 99% of patients with either no nodes examined or pathologic node negative. However, post-2015 patients were more likely to be pathologic node-negative (69.8% vs 41.6%, P < 0.001) (Table 1).

Table 1

Patient demographics and tumor characteristics.

Pre-2015 Post-2015 P
n = 39,130 n = 6986
Age (mean, s.d.) 48.9, 14.5 49.7, 14.7 <0.001*
Age older than 55 years 12,796 (32.7%) 2576 (36.9%) <0.001*
Female sex 30,921 (79.0%) 5575 (79.8%) 0.14
Race White 31,964 (81.7%) 5637 (80.7%) <0.001*
Black 2813 (7.2%) 385 (5.5%)
Asian or Pacific Islander 3716 (9.5%) 781 (11.2%)
American Indian/Alaska native 236 (0.6%) 55 (0.8%)
Unknown 401 (1.0%) 128 (1.8%)
Race comparison White 31,964 (81.7%) 5637 (80.7%) 0.048*
Non-White 7166 (18.3%) 1349 (19.3%)
Ethnicity Hispanic 5465 (14.0%) 1222 (17.5%) <0.001*
Median household income $50,000+ 34,367 (87.8%) 6253 (89.5%) <0.001*
Urban/rural residence Metropolitan area 35,434 (90.6%) 6355 (91.1%) 0.26
Histology Follicular 3531 (9.0%) 494 (7.1%) <0.001*
Papillary 35,599 (91.0%) 6492 (92.9%)
Lymph Nodes Node positive 0 (0.0%) 34 (0.5%) <0.001*
Node negative 16,260 (41.6%) 4877 (69.8%)
No nodes examined 22,797 (58.3%) 2056 (29.4%)
Positive aspiration or core biopsy of lymph node(s) 0 (0.0%) 4 (0.1%)
Not documented 73 (0.2%) 15 (0.2%)
Pathological T stage T1 24,303 (62.1%) 4478 (64.1%) 0.002*
T2 14,827 (37.9%) 2508 (35.9%)

*indicates statistical significance.

National trends

The Cochran–Armitage test showed that there was an increasing trend for lobectomy from 2004 to 2018 (P < 0.001), with an overall increase from 11.6% in 2004–2015 to 18.9% in 2016–2018 (P < 0.001). However, every year TT still outnumbered TL.

Disparities analysis

Univariate analysis of the pre-2015 cohort showed that patients who underwent TL were significantly older (age >55, 36.0% vs 32.3%, P < 0.001), less often White (80% vs 81.9%, P = 0.001), less likely to have a household income over $50,000 (85.6% vs 88.1%, P < 0.001), and less likely to live in a metropolitan area (88.9% vs 90.9%, P < 0.001) (Table 2). In the post-2015 cohort, those who underwent TL were also less often White (77.7% vs 81.4%, P = 0.002), but now more likely to have a median household income over $50,000 (92.1% vs 88.9%, P < 0.001) and more likely to live in a metropolitan area (92.8% vs 90.7%, P = 0.01), with no difference by ethnicity (Table 3).

Table 2

Demographics by surgical approach, pre-2015.

Variable Lobectomy Thyroidectomy P
n = 4545 n = 34,585
Age (mean, s.d.) 50.0, 15.4 48.8, 14.4 <0.001*
Age 55 years or older 1637 (36.0%) 11,159 (32.3%) <0.001*
Female sex 3466 (76.3%) 27,455 (79.4%) <0.001*
Race White 3634 (80.0%) 28,330 (81.9%) <0.001*
Black 403 (8.9%) 2410 (7.0%)
Asian or Pacific Islander 417 (9.2%) 3299 (9.5%)
American Indian/Alaska native 25 (0.6%) 211 (0.6%)
Unknown 66 (1.5%) 335 (1.0%)
Race comparison White 3634 (80.0%) 28,330 (81.9%) 0.001*
Non-White 911 (20.0%) 6255 (18.1%)
Ethnicity Hispanic 592 (13.0%) 4873 (14.1%) 0.05
Median household income $50,000+ 3890 (85.6%) 30,477 (88.1%) <0.001*
Urban/rural residence Metropolitan area 4034 (88.9%) 31,400 (90.9%) <0.001*

*indicates statistical significance.

Table 3

Demographics by surgical approach, post-2015.

Lobectomy Thyroidectomy P
n = 1323 n = 5663
Age (mean, s.d.) 48.4, 15.2 50.0, 14.5 <0.001*
Age 55 years or older 1637 (36.0%) 11,159 (32.3%) 0.13
Female sex 464 (35.1%) 2112 (37.3%) <0.001*
Race White 1028 (77.7%) 4609 (81.4%) 0.007*
Black 79 (6.0%) 306 (5.4%)
Asian or Pacific Islander 168 (12.7%) 613 (10.8%)
American Indian/Alaska native 11 (0.8%) 44 (0.8%)
Unknown 37 (2.8%) 91 (1.6%)
Race comparison White 1028 (77.7%) 4609 (81.4%) 0.002*
Non-White 295 (22.3%) 1054 (18.6%)
Ethnicity Hispanic 208 (15.7%) 1014 (17.9%) 0.06
Median household income $50,000+ 1218 (92.1%) 5035 (88.9%) <0.001*
Urban/rural residence Metropolitan area 1226 (92.8%) 5129 (90.7%) 0.01*

*indicates statistical significance.

Multivariable logistic regression was used to model the probability of undergoing TL while controlling for the significant differences identified in the univariate analysis, including age, metropolitan area, T stage, and histology. In the pre-2015 cohort, those who were older (OR 1.11, 95% CI 1.04–1.19, P < 0.001), lived in a non-metropolitan area (OR 1.16, 95% CI 1.05–1.28, P = 0.004), or had follicular carcinoma (OR 2.30, 95% CI 2.11–2.52, P < 0.001) were more likely to undergo TL. Patients undergoing TL were also more likely to have T2 disease (OR 1.11, 95% CI 1.04–1.19, P = 0.001) on final pathology than those who underwent TT. After 2015, patients with follicular carcinoma were still more likely to receive TL, but those who were older (OR 0.88, 95% CI 0.76–0.95, P = 0.006) or lived in a non-metropolitan area (OR 0.71, 95% CI 0.57–0.90, P = 0.004) were now less likely to undergo TL (Table 4). Patients who underwent TL post-2015 were more likely to have pathologic T1 disease (OR 0.81, 95% CI 0.71–0.92, P = 0.002) than those who underwent TT.

Table 4

Multivariable logistic regression model of thyroid lobectomy. The variables included in the model were age, residence type, T stage, nodal status, histology, and the interaction terms of time period (pre-/post-2015). Hence, the model estimates (OR and 95% CI) reported were stratified by time periods.

Variable Comparison Pre-2015 Post-2015
OR 95% CI P OR 95% CI P
Age >55 vs ≤55 1.11 1.04 1.19 0.001 0.84 0.73 0.95 0.006
Urban/rural Non-metropolitan vs metropolitan 1.16 1.05 1.28 0.004 0.71 0.57 0.90 0.004
T stage T2 vs T1 1.11 1.04 1.19 0.001 0.81 0.71 0.92 0.002
Histology Follicular vs papillary 2.30 2.11 2.52 <0.001 2.26 1.83 2.78 <0.001

Difference-in-difference analysis showed that after accounting for secular trends, which controls for both measured and unmeasured confounders over time, there were still several significant interactions. Comparing pre-2015 to post-2015, patients over 55 were significantly less likely to receive TL after 2015 (P < 0.001). Living in a metropolitan area also had a significant interaction, where those who lived in non-metropolitan areas were significantly less likely to receive TL after 2015 (P < 0.001). Difference-in-difference analysis also showed that after 2015, patients with T1 disease were more likely to receive TL than those with T2 disease (P < 0.001) (Fig. 1).

Figure 1
Figure 1

Difference-in-difference analysis of TL for low-risk DTC.

Citation: Endocrine Oncology 4, 1; 10.1530/EO-24-0010

Discussion

In 2015, the ATA updated their recommendations to include thyroid lobectomy as the appropriate treatment for low-risk differentiated thyroid cancer. Several studies using national databases have demonstrated that since this guideline change, the rate of thyroid lobectomy has increased. For example, Ullmann et al. used the National Surgery Quality Improvement Program data and found a significant increase in the rate of TL after the guideline update without a concurrent increase in completion thyroidectomy (Ullmann et al. 2019). Toumi et al. used the IBM MarketScan Database and also found that the proportion of TT compared to TL dropped significantly after the guideline change, from 80% to 39% (Toumi et al. 2021). Our study confirmed this finding using the population-based SEER database, with a significantly increasing trend in TL from 2004 to 2018.

We also identified discrepancies in who received TL for appropriately low-risk DTC. Multivariable analysis showed that after 2015, age over 55 and living in a non-metropolitan area were both independently associated with not undergoing TL, and difference-in-difference analysis confirmed that this remained significant even after controlling for unmeasured secular confounders. It is worth emphasizing that this discrepancy was found using a population-based cancer registry, which is not restricted to Cancer-on-Commission accredited centers. Thus, these findings pertain to the general U.S. population of patients and surgeons, which were not necessarily represented in the findings published recently by Gordon et al. and Ginzberg et al., who both used the National Cancer Database (NCDB) (Gordon et al. 2022, Ginzberg et al. 2023). Gordon et al. found that guideline compliance was significantly higher at academic centers but with no difference by patient age, sex, or race, whereas Ginzberg et al. showed that racial and ethnic disparities in treatment improved after the guideline update (Gordon et al. 2022, Ginzberg et al. 2023). In contrast, our study found significant differences in the utilization of TL for patients over 55 and those who live in non-metropolitan neighborhoods. Given that low-volume surgeons perform the majority of thyroidectomies in the US and may not be included in the NCDB (McDow et al. 2021b), these findings may be more representative of the general population.

Our findings complement those recently published by Collins et al., as they also used the SEER database to evaluate patients with low-risk papillary thyroid carcinoma. They found that before 2015, patients in metropolitan areas were less likely to undergo TL than those in non-metropolitan areas (16.9% vs 20.1%). After the guideline change, this equalized to 25.7% and 24.5%, respectively (Collins et al. 2023). While our analysis was conducted differently, this general trend is consistent with our results. We found that before 2015, patients who underwent TL were less likely to live in a metropolitan area, whereas after 2015, they were more likely. Our difference-in-difference analysis showed that this shift towards TL in metropolitan areas was significant. This means we did not find as big of a shift towards TL in the non-metropolitan population as they did, which could be explained by the fact that Collins et al. included patients with tumors <1 cm and found that patients from rural settings were significantly more likely to have subcentimeter tumors. We excluded patients with tumors <1 cm because the management of subcentimeter tumors did not change in the 2015 ATA guideline update.

We also found differences in T stage between the pre-2015 and post-2015 cohorts. Before 2015, patients who underwent TL were more likely to have T2 disease on final pathology, whereas post-2015, TL patients were more likely to have T1 disease. The significance of T1 vs T2 disease on final pathology is difficult to interpret given the absence of clinical T stage data; however, this is consistent with published data from CESQIP. Wrenn et al. found that from 2014 to 2019, TL for low-risk PTC was used 24% of the time in tumors <1 cm (T1a), 16% of the time in tumors 1–2 cm in size (T1b), and only 6% of the time for tumors 2–4 cm in size (T2) (Wrenn et al. 2021). This suggests that despite the guideline change, there is still a reluctance to pursue TL for T2 tumors.

These findings raise two pertinent questions: Why is TT still more commonly performed for low-risk DTC than TL? And why are there differences in who is offered TL? For the first question, McDow et al. surveyed over 300 surgeons registered with the American Medical Association in 2021 and found that low-volume surgeons were less likely than high-volume surgeons to be aware of the new ATA guidelines supporting TL for low-risk PTC and less likely to follow clinical practice guidelines at all (McDow et al. 2021a). In addition, nearly 20% of respondents believed recurrence is more likely after TL than TT, and only 12% believed that quality of life is better after TL (McDow et al. 2021b). Altogether, it is conceivable that surgeon preference and experience are superseding national guidelines, especially given that TT is still considered guideline-compliant therapy for low-risk DTC to enable radioactive iodine (RAI) therapy or to enhance follow-up based on disease features and/or patient preference (Haugen et al. 2016).

As for the sociodemographic differences, our study showed that older patients are less likely to receive TL for low-risk DTC. One possible reason for this is that younger patients may preferentially undergo TL to avoid lifelong thyroid hormone replacement therapy. While this concept may favor the younger patients who have a presumably longer time living without needing levothyroxine, retrospective studies have shown that up to 60-70% of patients still require thyroid hormone replacement after lobectomy for DTC (Kim et al. 2020, Schumm et al. 2021), and recent findings from the North American Thyroid Cancer Survivorship Study showed that patients with thyroid cancer report a worse quality of life than patients with breast or colorectal cancer, largely due to the impact of thyroid testing and symptoms related to hypothyroidism and hyperthyroidism (Aschebrook-Kilfoy et al. 2015). That said, if thyroid hormone replacement is required, TL is associated with lower doses of levothyroxine and fewer adjustments to reach euthyroidism (Kluijfhout et al. 2016). Thus, avoiding complete thyroid hormone replacement may be one of the greater benefits of TL in these low-risk DTC patients.

We also found that those living in non-metropolitan areas were less likely to undergo TL when guideline-appropriate. Living in a metropolitan area is likely correlated with receiving care at academic centers, which, as discussed before, are more guideline-compliant (Gordon et al. 2022). Even so, this finding carries its own significant implications. TT is associated with higher rates of temporary vocal cord paralysis and both temporary and permanent hypoparathyroidism compared to TL (Chun et al. 2015, Gunn et al. 2020, Hsiao et al. 2022). Expedient treatment of these complications may be more difficult to attain in rural locations and certainly may be more detrimental to the older population with less physical reserve. There are likely a multitude of factors contributing to this disparity that are not captured in the SEER database; these warrant further investigation and review.

There are several limitations to this study. Importantly, the SEER database only captures 48% of the US population, as cancer registries have not yet been established in every state. Additionally, it lacks data on patient insurance, hospital affiliation, and accreditation status, as well as follow-up data on whether patients underwent completion thyroidectomy or RAI therapy after their index operation. Clinical T stage for thyroid cancer was also only collected for select years, and so it could not be included in our analysis. Lastly, SEER provides data on residence in metropolitan vs non-metropolitan areas, but this may not always correlate with where the patient received care. In addition, only data up to 2018 were utilized as that was what was available at the time of study design. A more contemporary evaluation of the data may be more representative of current practice patterns. Lastly, as with any national database, there are also potential issues with data completeness, accuracy, and selection bias. However, this database captures all cancers in registered states and, as such, is primed for evaluating national trends in treatment.

Conclusions

In conclusion, rates of thyroid lobectomy increased significantly after the updated 2015 ATA guidelines, but more so for pathological T1 tumors and younger patients living in metropolitan areas. Older patients and those living in non-metropolitan areas were significantly less likely to undergo TL for low-risk DTC. There are a multitude of potential explanations for this; however, it is important to recognize that these guidelines were established to minimize risks associated with total thyroidectomy while ensuring appropriate oncologic outcomes and that not all patients are benefiting from this. This is an important area for growth in the field of surgery. There is a role for academic societies to take the lead in the dissemination of up-to-date research and guidelines. The integration of the ATA guidelines into the electronic medical record may also encourage compliance and consistency. Further work into how best to encourage guideline adherence is needed for surgeons and patients alike.

Declaration of interest

The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the study reported.

Funding

This work did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Author contribution statement

PGL helped conceive the study, interpreted data, and wrote the manuscript. ZVF helped with data analysis and interpretation and manuscript review. PTH, NW, and PAC assisted with manuscript review. YHC and ESL performed data collection and statistical analysis. CCS conceived the study, assisted with interpretation of the results, and edited the manuscript.

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  • Haigh PI, Urbach DR & & Rotstein LE 2005 Extent of thyroidectomy is not a major determinant of survival in low- or high-risk papillary thyroid cancer. Annals of Surgical Oncology 12 8189. (https://doi.org/10.1007/s10434-004-1165-1)

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  • Haugen BR, Alexander EK, Bible KC, Doherty GM, Mandel SJ, Nikiforov YE, Pacini F, Randolph GW, Sawka AM, Schlumberger M, et al.2016 2015 American Thyroid Association management guidelines for adult patients with thyroid nodules and differentiated thyroid cancer The American Thyroid Association guidelines task force on thyroid nodules and differentiated thyroid cancer. Thyroid 26 1133. (https://doi.org/10.1089/thy.2015.0020)

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  • Hsiao V, Light TJ, Adil AA, Tao M, Chiu AS, Hitchcock M, Arroyo N, Fernandes-Taylor S & & Francis DO 2022 Complication rates of total thyroidectomy vs hemithyroidectomy for treatment of papillary thyroid microcarcinoma: a systematic review and meta-analysis. JAMA Otolaryngology Head and Neck Surgery 148 531539. (https://doi.org/10.1001/jamaoto.2022.0621)

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  • Kim SY, Kim HJ, Kim SM, Chang H, Lee YS, Chang HS & & Park CS 2020 Thyroid hormone supplementation therapy for differentiated thyroid cancer after lobectomy: 5 years of follow-up. Frontiers in Endocrinology 11 520. (https://doi.org/10.3389/fendo.2020.00520)

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  • Kluijfhout WP, Rotstein LE & & Pasternak JD 2016 Well-differentiated thyroid cancer: thyroidectomy or lobectomy? Canadian Medical Association Journal 188 E517E520. (https://doi.org/10.1503/cmaj.160336)

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  • Matsuzu K, Sugino K, Masudo K, Nagahama M, Kitagawa W, Shibuya H, Ohkuwa K, Uruno T, Suzuki A, Magoshi S, et al.2014 Thyroid lobectomy for papillary thyroid cancer: long-term follow-up study of 1,088 cases. World Journal of Surgery 38 6879. (https://doi.org/10.1007/s00268-013-2224-1)

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  • McDow AD, Roman BR, Saucke MC, Jensen CB, Zaborek N, Jennings JL, Davies L, Brito JP & & Pitt SC 2021a Factors associated with physicians' recommendations for managing low-risk papillary thyroid cancer. American Journal of Surgery 222 111118. (https://doi.org/10.1016/j.amjsurg.2020.11.021)

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  • McDow AD, Saucke MC, Marka NA, Long KL & & Pitt SC 2021b Thyroid lobectomy for low-risk papillary thyroid cancer: a national survey of low- and high-volume surgeons. Annals of Surgical Oncology 28 35683575. (https://doi.org/10.1245/s10434-021-09898-9)

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  • Mendelsohn AH, Elashoff DA, Abemayor E & St John MA 2010 Surgery for papillary thyroid carcinoma: is lobectomy enough? Archives of Otolaryngology Head and Neck Surgery 136 10551061. (https://doi.org/10.1001/archoto.2010.181)

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  • Nixon IJ, Ganly I, Patel SG, Palmer FL, Whitcher MM, Tuttle RM, Shaha A & & Shah JP 2012 Thyroid lobectomy for treatment of well differentiated intrathyroid malignancy. Surgery 151 571579. (https://doi.org/10.1016/j.surg.2011.08.016)

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  • Schumm MA, Lechner MG, Shu ML, Ochoa JE, Kim J, Tseng CH, Leung AM & & Yeh MW 2021 Frequency of thyroid hormone replacement after lobectomy for differentiated thyroid cancer. Endocrine Practice 27 691697. (https://doi.org/10.1016/j.eprac.2021.01.004)

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  • Schvartz C, Bonnetain F, Dabakuyo S, Gauthier M, Cueff A, Fieffe S, Pochart JM, Cochet I, Crevisy E, Dalac A, et al.2012 Impact on overall survival of radioactive iodine in low-risk differentiated thyroid cancer patients. Journal of Clinical Endocrinology and Metabolism 97 15261535. (https://doi.org/10.1210/jc.2011-2512)

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  • Toumi A, DiGennaro C, Vahdat V, Jalali MS, Gazelle GS, Chhatwal J, Kelz RR & & Lubitz CC 2021 Trends in thyroid surgery and guideline-concordant care in the United States, 2007–2018. Thyroid 31 941949. (https://doi.org/10.1089/thy.2020.0643)

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  • Ullmann TM, Gray KD, Stefanova D, Limberg J, Buicko JL, Finnerty B, Zarnegar R, Fahey TJ 3rd & & Beninato T 2019 The 2015 American Thyroid Association guidelines are associated with an increasing rate of hemithyroidectomy for thyroid cancer. Surgery 166 349355. (https://doi.org/10.1016/j.surg.2019.03.002)

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  • Wrenn SM, Wang TS, Toumi A, Kiernan CM, Solorzano CC & & Stephen AE 2021 Practice patterns for surgical management of low-risk papillary thyroid cancer from 2014 to 2019: a CESQIP analysis. American Journal of Surgery 221 448454. (https://doi.org/10.1016/j.amjsurg.2020.07.032)

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  • Aschebrook-Kilfoy B, James B, Nagar S, Kaplan S, Seng V, Ahsan H, Angelos P, Kaplan EL, Guerrero MA, Kuo JH, et al.2015 Risk factors for decreased quality of life in thyroid cancer survivors: initial findings from the North American thyroid cancer survivorship study. Thyroid 25 13131321. (https://doi.org/10.1089/thy.2015.0098)

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  • Barney BM, Hitchcock YJ, Sharma P, Shrieve DC & & Tward JD 2011 Overall and cause-specific survival for patients undergoing lobectomy, near-total, or total thyroidectomy for differentiated thyroid cancer. Head and Neck 33 645649. (https://doi.org/10.1002/hed.21504)

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  • Chun BJ, Bae JS, Lee SH, Joo J, Kim ES & & Sun DI 2015 A prospective randomized controlled trial of the laryngeal mask airway versus the endotracheal intubation in the thyroid surgery: evaluation of postoperative voice, and laryngopharyngeal symptom. World Journal of Surgery 39 17131720. (https://doi.org/10.1007/s00268-015-2995-7)

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  • Collins RA, Chaves N, Lee G, Broekhuis JM & & James BC 2023 Urban and rural surgical practice patterns for papillary thyroid carcinoma. Thyroid 33 849857. (https://doi.org/10.1089/thy.2022.0711)

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  • Ginzberg SP, Soegaard Ballester JM, Wirtalla CJ, Morales KH, Pryma DA, Mandel SJ, Kelz RR & & Wachtel H 2023 Racial and ethnic disparities in appropriate thyroid cancer treatment, before and after the release of the 2015 American Thyroid Association guidelines. Annals of Surgical Oncology 30 29282937. (https://doi.org/10.1245/s10434-023-13158-3)

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  • Gordon AJ, Dublin JC, Patel E, Papazian M, Chow MS, Persky MJ, Jacobson AS, Patel KN, Suh I, Morris LGT, et al.2022 American Thyroid Association guidelines and national trends in management of papillary thyroid carcinoma. JAMA Otolaryngology Head and Neck Surgery 148 11561163. (https://doi.org/10.1001/jamaoto.2022.3360)

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  • Gunn A, Oyekunle T, Stang M, Kazaure H & & Scheri R 2020 Recurrent laryngeal nerve injury after thyroid surgery: an analysis of 11,370 patients. Journal of Surgical Research 255 4249. (https://doi.org/10.1016/j.jss.2020.05.017)

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  • Haigh PI, Urbach DR & & Rotstein LE 2005 Extent of thyroidectomy is not a major determinant of survival in low- or high-risk papillary thyroid cancer. Annals of Surgical Oncology 12 8189. (https://doi.org/10.1007/s10434-004-1165-1)

    • PubMed
    • Search Google Scholar
    • Export Citation
  • Haugen BR, Alexander EK, Bible KC, Doherty GM, Mandel SJ, Nikiforov YE, Pacini F, Randolph GW, Sawka AM, Schlumberger M, et al.2016 2015 American Thyroid Association management guidelines for adult patients with thyroid nodules and differentiated thyroid cancer The American Thyroid Association guidelines task force on thyroid nodules and differentiated thyroid cancer. Thyroid 26 1133. (https://doi.org/10.1089/thy.2015.0020)

    • PubMed
    • Search Google Scholar
    • Export Citation
  • Hsiao V, Light TJ, Adil AA, Tao M, Chiu AS, Hitchcock M, Arroyo N, Fernandes-Taylor S & & Francis DO 2022 Complication rates of total thyroidectomy vs hemithyroidectomy for treatment of papillary thyroid microcarcinoma: a systematic review and meta-analysis. JAMA Otolaryngology Head and Neck Surgery 148 531539. (https://doi.org/10.1001/jamaoto.2022.0621)

    • PubMed
    • Search Google Scholar
    • Export Citation
  • Kim SY, Kim HJ, Kim SM, Chang H, Lee YS, Chang HS & & Park CS 2020 Thyroid hormone supplementation therapy for differentiated thyroid cancer after lobectomy: 5 years of follow-up. Frontiers in Endocrinology 11 520. (https://doi.org/10.3389/fendo.2020.00520)

    • PubMed
    • Search Google Scholar
    • Export Citation
  • Kluijfhout WP, Rotstein LE & & Pasternak JD 2016 Well-differentiated thyroid cancer: thyroidectomy or lobectomy? Canadian Medical Association Journal 188 E517E520. (https://doi.org/10.1503/cmaj.160336)

    • PubMed
    • Search Google Scholar
    • Export Citation
  • Matsuzu K, Sugino K, Masudo K, Nagahama M, Kitagawa W, Shibuya H, Ohkuwa K, Uruno T, Suzuki A, Magoshi S, et al.2014 Thyroid lobectomy for papillary thyroid cancer: long-term follow-up study of 1,088 cases. World Journal of Surgery 38 6879. (https://doi.org/10.1007/s00268-013-2224-1)

    • PubMed
    • Search Google Scholar
    • Export Citation
  • McDow AD, Roman BR, Saucke MC, Jensen CB, Zaborek N, Jennings JL, Davies L, Brito JP & & Pitt SC 2021a Factors associated with physicians' recommendations for managing low-risk papillary thyroid cancer. American Journal of Surgery 222 111118. (https://doi.org/10.1016/j.amjsurg.2020.11.021)

    • PubMed
    • Search Google Scholar
    • Export Citation
  • McDow AD, Saucke MC, Marka NA, Long KL & & Pitt SC 2021b Thyroid lobectomy for low-risk papillary thyroid cancer: a national survey of low- and high-volume surgeons. Annals of Surgical Oncology 28 35683575. (https://doi.org/10.1245/s10434-021-09898-9)

    • PubMed
    • Search Google Scholar
    • Export Citation
  • Mendelsohn AH, Elashoff DA, Abemayor E & St John MA 2010 Surgery for papillary thyroid carcinoma: is lobectomy enough? Archives of Otolaryngology Head and Neck Surgery 136 10551061. (https://doi.org/10.1001/archoto.2010.181)

    • PubMed
    • Search Google Scholar
    • Export Citation
  • Nixon IJ, Ganly I, Patel SG, Palmer FL, Whitcher MM, Tuttle RM, Shaha A & & Shah JP 2012 Thyroid lobectomy for treatment of well differentiated intrathyroid malignancy. Surgery 151 571579. (https://doi.org/10.1016/j.surg.2011.08.016)

    • PubMed
    • Search Google Scholar
    • Export Citation
  • Schumm MA, Lechner MG, Shu ML, Ochoa JE, Kim J, Tseng CH, Leung AM & & Yeh MW 2021 Frequency of thyroid hormone replacement after lobectomy for differentiated thyroid cancer. Endocrine Practice 27 691697. (https://doi.org/10.1016/j.eprac.2021.01.004)

    • PubMed
    • Search Google Scholar
    • Export Citation
  • Schvartz C, Bonnetain F, Dabakuyo S, Gauthier M, Cueff A, Fieffe S, Pochart JM, Cochet I, Crevisy E, Dalac A, et al.2012 Impact on overall survival of radioactive iodine in low-risk differentiated thyroid cancer patients. Journal of Clinical Endocrinology and Metabolism 97 15261535. (https://doi.org/10.1210/jc.2011-2512)

    • PubMed
    • Search Google Scholar
    • Export Citation
  • Toumi A, DiGennaro C, Vahdat V, Jalali MS, Gazelle GS, Chhatwal J, Kelz RR & & Lubitz CC 2021 Trends in thyroid surgery and guideline-concordant care in the United States, 2007–2018. Thyroid 31 941949. (https://doi.org/10.1089/thy.2020.0643)

    • PubMed
    • Search Google Scholar
    • Export Citation
  • Ullmann TM, Gray KD, Stefanova D, Limberg J, Buicko JL, Finnerty B, Zarnegar R, Fahey TJ 3rd & & Beninato T 2019 The 2015 American Thyroid Association guidelines are associated with an increasing rate of hemithyroidectomy for thyroid cancer. Surgery 166 349355. (https://doi.org/10.1016/j.surg.2019.03.002)

    • PubMed
    • Search Google Scholar
    • Export Citation
  • Wrenn SM, Wang TS, Toumi A, Kiernan CM, Solorzano CC & & Stephen AE 2021 Practice patterns for surgical management of low-risk papillary thyroid cancer from 2014 to 2019: a CESQIP analysis. American Journal of Surgery 221 448454. (https://doi.org/10.1016/j.amjsurg.2020.07.032)

    • PubMed
    • Search Google Scholar
    • Export Citation