Succinate dehydrogenase B gene mutations predict survival in patients with malignant pheochromocytomas or paragangliomas

Context: Pheochromocytomas and paragangliomas may be malignant either at presentation or during recurrence, but the clinical course of malignant tumors is unpredictable. Objective: The objective was to analyze survival according to clinical characteristics at diagnosis of malignancy and the presence or absence of SDHB mutations. Design: This was a retrospective cohort study. Setting and Participants: A total of 54 patients with malignant tumors were included. Malignancy was scored according to the presence of metastases or histologically documented lymph node invasion. Main Outcome Measures: The main outcome was the specific survival after the diagnosis of the first metastasis. Results: Germline mutations were identified in SDHB (n = 23, including 21 patients with apparent sporadic tumors) and VHL (n = 1) genes, and two patients had neurofibromatosis 1. Patients were followed up from the diagnosis of primary tumor and from the diagnosis of the first metastasis to the present or to death with medians of 79 [interquartile range (IQR) 24; 190] and 39 [IQR 14; 94] months, respectively. The 5-yr probability of survival after the diagnosis of the first metastasis was 0.55 (95% confidence interval 0.39-0.69). Patients with SDHB mutations were younger, more frequently had extra-adrenal tumors, and had a shorter metanephrine excretion doubling time. The presence of SDHB mutations was significantly and independently associated with mortality (relative risk 2.7; 95% confidence interval 1.2, 6.4; P = 0.021). Conclusion: SDHB mutations, frequent in patients with malignant pheochromocytomas or paragangliomas, are associated with shorter survival. Therefore, SDHB genetic testing may be of prognostic value for such patients, even those with an apparent sporadic and/or benign presentation at diagnosis.