The Impact of Adjuvant Radiotherapy Administration on Disease-Specific Survival in Patients with Parathyroid Carcinoma

INTRODUCTION: The effect of adjuvant radiotherapy (AR) on disease-specific survival (DSS) in patients with parathyroid carcinoma remains unclear. We explored the impact of AR on DSS.

METHODS: Patients with parathyroid carcinoma were identified in SEER and categorized based on AR administration. To address confounding factors affecting the nonrandom allocation of radiotherapy, we conducted propensity score matching. We then employed Kaplan-Meier survival analysis to estimate DSS.

RESULTS: In total, 549 patients were included, with 64 (11.6%) receiving AR. Those who received AR had larger tumors, measuring 3.2 (interquartile range 2.3-4.5) cm compared with 2.7 (interquartile range 1.8-3.5) cm than those who did not receive AR (p = 0.01). Patients who received AR exhibited improved 10- (90.3% vs. 72.2%, p = 0.02) and 20 year DSS (90% vs. 68%, p = 0.03). Our multivariable Cox regression confirmed that patients who did not receive AR had poorer DSS [3.2, 95% CI 1.3-10.1]. Furthermore, non-Hispanic ethnicity [Hispanic patients: 0.13, 95% CI 0.007-0.7], extraparathyroidal extension (EPE) [2.7, 95% CI 1.1-6.9], and positive lymph node status [10.2, 95% CI 1.6-47.8] were linked to diminished DSS.

CONCLUSIONS: Using propensity-score matching in a large database, AR in patients with parathyroid carcinoma was associated with improved DSS compared with matched patients who did not receive AR. Notably, the lack of AR administration was identified as an independent factor linked to poorer DSS [3.2, 95% CI 1.3-10.1]. These findings indicate that AR should be considered by clinicians when dealing with these rare tumors and prospective studies are warranted to further assess its role.