Margin Free Resection Achieves Excellent Long Term Outcomes in Parathyroid Cancer

SIMPLE SUMMARY: Long-term outcomes of parathyroid cancer are unsatisfactory with common locoregional recurrence and significant mortality. Our case series provides evidence that an oncological surgical approach lastingly benefits patients, affording a 10-year disease-specific survival rate of 100%. Core principles are pre-operative recognition of potential malignancy, en-bloc resection ensuring cancer free resection margins (R0) and clearance of the central lymph node compartment, followed by initially dense follow-up for timely detection and aggressive treatment of recurrence. ABSTRACT: Long-term outcomes of parathyroid cancer remain poorly documented and unsatisfactory. This cohort includes 25 consecutive parathyroid cancer patients with median follow-up of 10.7 years (range 4.1–26.5 years). Pre-operative work-up in the center identified a suspicion of parathyroid cancer in 17 patients. En bloc resection, including the recurrent laryngeal nerve in 4/17 (23.5%), achieved cancer-free resection margins (R0) in 82.4% and lasting loco-regional disease control in 94.1%. Including patients referred after initial surgery elsewhere, R0 resection was achieved in merely 17/25 (68.0%) of patients. Cancer-positive margins (R1) in 8 patients led to local recurrence in 50%. On multivariate analysis, only margin status prevailed as independent predictor of recurrence free survival (χ(2) 19.5, p < 0.001). Local excision alone carried a 3.5-fold higher risk of positive margins than en bloc resection (CI(95): 1.1–11.3; p = 0.03), and a 6.4-fold higher risk of locoregional recurrence (CI(95): 0.8–52.1; p = 0.08). R1-status was associated with an 18.0-fold higher risk of recurrence and redo surgery (CI(95): 1.1–299.0; p = 0.04), and a 22.0-fold higher probability of radiation (CI(95): 1.4–355.5; p = 0.03). In patients at risk, adjuvant radiation reduced the actuarial risk of locoregional recurrence (p = 0.05). When pre-operative scrutiny resulted in upfront oncological surgery achieving cancer free margins, it afforded 100% recurrence free survival at 5- and 10-year follow-up, whilst failure to achieve clear margins caused significant burden by outpatient admissions (176 vs. 4 days; χ(2) 980, p < 0.001) and exposure to causes for concern (1369 vs. 0 days; χ(2) 11.3, p = 0.003). Although limited by cohort size, our study emphasizes the paradigm of getting it right the first time as key to improve survivorship in a cancer with excellent long-term prognosis.