Prognosis of Malignant Pheochromocytoma and Paraganglioma (MAPP-Prono Study): A European Network for the Study of Adrenal Tumors Retrospective Study

Background: Malignant pheochromocytoma and paraganglioma (MPP) are characterized by prognostic heterogeneity. Our objective was to look for prognostic parameters of overall survival (OS) in MPP patients. Patients and Methods: Retrospective multicenter study of MPP characterized by a neck-thoraco-abdomino-pelvic CT or MRI at the time of malignancy diagnosis in European centers between 1998 and 2010. Results: One hundred sixty-nine patients from 18 European centers were included. Main characteristics of patients with MPP were: primary pheochromocytoma in 53% of patients; tumor- or hormone-related symptoms in 57% or 58% of cases; positive plasma or urine hormones in 81% of patients; identification of a mutation in SDHB in 42% of cases. Metastatic sites included bone (64%), lymph node (40%), lung (29%), and liver (26%); mean time between initial and malignancy diagnosis was 43 months (range, 0 to 614). Median follow-up was 68 months and median survival 6.7 years. Using univariate analysis, better survival was associated with head and neck paraganglioma, age <40 years, metanephrines less than fivefold the upper limits of the normal range, and low proliferative index. In multivariate analysis, hypersecretion [hazard ratio 3.02 (1.65 to 5.55); P = 0.0004] was identified as an independent significant prognostic factor of worst OS. Conclusions: Our results do not confirm SDHB mutations as a major prognostic parameter in MPP and suggest additional key molecular events involved in MPP tumor progression. Aside from SDHB mutation, the biology of aggressive MPP remains to be understood.