Limited Thyroidectomy Achieves Equivalent Survival to Total Thyroidectomy for Early Localized Medullary Thyroid Cancer

Abstract

Background: The optimal surgical approach for localized T1 medullary thyroid cancer remains unclear. Total thyroidectomy is standard, but lobectomy and subtotal thyroidectomy may minimize mortality while maintaining oncologic control.

Methods: This retrospective analysis utilized the National Cancer Institute's Surveillance, Epidemiology, and End Results registry to identify 2702 MTC patients including 398 patients with T1N0/1M0 MTC treated with total thyroidectomy or lobectomy/subtotal thyroidectomy from 2000 to 2019. Cox regression analyses assessed thyroid cancer-specific and overall mortality.

Results: The majority (89.7%) underwent total thyroidectomy, while 10.3% had lobectomy/subtotal thyroidectomy. Nodal metastases were present in 29.6%. Over a median follow-up of 8.75 years, no significant difference was observed in cancer-specific mortality (5.7% vs. 8.1%, p = 0.47) or overall mortality (13.2% vs. 12.8%, p = 0.95). On multivariate analysis, undergoing cancer-directed surgery was associated with significantly improved overall survival (HR 0.18, p < 0.001) and cancer-specific survival (HR 0.17, p < 0.001) compared to no surgery. However, no significant survival difference was seen between total thyroidectomy and lobectomy/subtotal thyroidectomy for overall mortality (HR 0.77, p = 0.60) or cancer-specific mortality (HR 0.44, p = 0.23). The extent of surgery also did not impact outcomes within subgroups stratified by age, gender, T stage, or nodal status. Delayed surgery >1 month after diagnosis was associated with worse overall survival (p = 0.012).

Conclusions: For localized T1 MTC, lobectomy/subtotal thyroidectomy appears to achieve comparable long-term survival to total thyroidectomy in this population-based analysis. The selective use of limited thyroidectomy may be reasonable for low-risk T1N0/1M0 MTC patients. Delayed surgery is associated with worse survival and additional neck dissection showed no benefit for this select group of patients.

Keywords: MTC; SEER; T1N0M0; T1N1M0; endocrine; lobectomy; medullary thyroid cancer; thyroidectomy.

Figure 1

Independent risk factors for second primary malignancies. The forest plot visually represents the analysis of various independent risk factors for second primary malignancies. Logistic regression analysis was used. Odds ratio (OR) and 95% confidence interval (CI) are rported. Each line on the plot corresponds to a different risk factor, with the red dot indicating the odds ratio and the horizontal line representing the confidence interval (spanning from the lower to the upper limit). API: Asian or Pacific Islander, AI/AN: Am. Indian/Alaska Native.

Figure 2

Kaplan–Meier survival curves in T1 MTC patients undergoing surgery vs. no surgery. (A) Overall survival. (B) Thyroid cancer-specific survival. Log-rank test was used.

Figure 3

Kaplan–Meier survival curves in T1 MTC patients undergoing total thyroidectomy versus lobectomy/subtotal thyroidectomy. (A) Overall survival. (B) Thyroid cancer-specific survival. Log-rank test was used.

Figure 4

Subgroup analysis comparing overall survival times in total thyroidectomy and lobectomy/subtotal thyroidectomy T1 MTC patients. The values of the mean in months and confidence intervals (CIs) are displayed on the plot for both lobectomy/subtotal thyroidectomy (blue) and total thyroidectomy (green) treatments. Log-rank test was used for comparisons.

Figure 5

Predictors of delayed onset of treatment in MTC patients. API: Asian or Pacific Islander. Logistic regression analysis was performed and odds ratio (OR) and 95% confidence intervals (CIs) were reported.

Figure 6

Kaplan–Meier survival curves in T1 MTC patients according to the timing of treatment. (A) Overall survival. (B) Thyroid cancer-specific survival. Log-rank test was used.