Oncologic Resection Achieving R0 Margins Improves Disease-Free Survival in Parathyroid Cancer

Background
Parathyroid cancer has a poor mid-term prognosis, often because of local recurrence, observed in half of all patients. Modern diagnostic workup increasingly enables a preoperative diagnosis of parathyroid cancer. There is limited evidence that more comprehensive oncologic surgery can reduce the risk of local recurrence. This study aims to identify the best specific surgical approach in parathyroid cancer.

Methods
This observational cohort study comprises 19 consecutive patients who had undergone oncologic or nononcologic resection for parathyroid cancer. Baseline parameters were compared by using univariate analysis; outcomes were assessed by chi (2) testing and Kaplan-Meier statistics.

Results
Fifteen of 19 patients were primarily operated on in our tertiary center between 1996 and 2013, and four were referred for follow-up because of their cancer diagnosis. Patient cohorts defined by histologic R-status were comparable for established risk factors: sex, calcium levels, low-risk/high-risk status, and presence of vascular invasion. Oncologic resections were performed in 13 of 15 patients primarily treated in the center and 0 of 4 treated elsewhere (chi (2) = 5.6; p < 0.01). R0 margins were achieved in 11 of 13 (85 %) undergoing oncologic resection and 1 of 6 (17 %) undergoing local excision (chi (2) = 8.1; p < 0.01). R0 margins and primary oncologic resection were associated with higher disease-free survival rates (chi (2) = 7.9; p = 0.005 and chi (2) = 4.7; p = 0.03, respectively). Revision surgery achieved R0 margins in only 2 of 4 (50 %) of patients.

Conclusions
In parathyroid cancer, a more comprehensive surgery (primary oncologic resection) provides significantly better outcomes than local excision as a result of reduction of R1 margins and locoregional recurrence.