Parathyroid carcinoma: Is there a role for adjuvant radiation therapy?

BACKGROUND: The authors proposed to determine risk factors associated with postoperative progression of parathyroid carcinoma within the neck (locoregional) and to assess the efficacy of postoperative adjuvant radiation therapy in preventing disease progression within the neck. METHODS: A retrospective review of patients with pathologically confirmed parathyroid carcinoma who underwent surgical resection was performed. Risk factors identified on univariate analysis were applied in a proportional hazards analysis to identify significant independent predictors of locoregional disease progression and cause-specific survival after surgical resection. Fifty-seven patients were treated with surgery alone (no adjuvant radiation therapy RT) and were determined to have sufficient follow-up and pathologically confirmed features to be included in the current analysis. Four patients were treated with surgery and adjuvant RT. Four patients received RT to the neck and mediastinum for unresectable locoregional disease progression. Patients were followed for a median of 75.6 months (range, 8.4-358 months). RESULTS: Twenty-five patients (44%) developed locoregional disease progression at a median of 27.1 months after surgery (range, 6.2-138.3 months). The univariate analysis revealed that surgical margin status and the institution at which the initial surgery was performed were predictive of locoregional progression-free survival. The institution at which the initial surgery was performed was found to be an independent predictor of cause-specific survival. Of the four patients treated with surgery and adjuvant RT, all were alive and without disease at the time of last follow-up. All four patients who received RT for locoregional disease progression after initial surgery achieved locoregional disease control. CONCLUSIONS: Patients with parathyroid carcinoma are reported to have a significant risk of locoregional disease progression after surgery alone. The results of the current study demonstrated that the risk of postoperative disease progression can be predicted by surgical margin status and the institution at which the initial surgery is performed. Patients treated with surgery and postoperative RT may have a lower risk of locoregional disease progression and improved cause-specific survival. RT can be used to provide locoregional control of recurrent disease.