Clinical Predictors of Malignancy in Patients with Pheochromocytoma and Paraganglioma

Mashaal Dhir, Wei Li, Melissa E. Hogg, David L. Bartlett, Sally E. Carty, Kelly L. McCoy, Sue M. Challinor, Linwah Yip

Factors associated with malignancy in patients with pheochromocytoma (adrenal tumors, Pheo) and paraganglioma (extra-adrenal, PGL) are not well-defined and all patients require lifelong surveillance. The primary aim of our study was to determine genetic and clinical variables associated with malignancy in patients with Pheo/PGL. Single institution retrospective review was performed of all patients who underwent surgery (1/95-1/15) for Pheo/PGL. Malignancy was defined as histology-confirmed distant metastasis, lymph nodal involvement, or tumor bed recurrence. A total of 157 Pheo/PGL patients (44 malignant, 113 benign) with mean follow-up of 87 months were included. Compared with patients with benign Pheo/PGL, patients with malignant Pheo/PGL were younger (median 42 vs 50 years, p = 0.014), had larger tumors (median 6.5 vs 4 cm, p < 0.001) and had PGL (63.6 vs 4.4%, p < 0.001). Genetic testing was performed in 60 patients and was positive in 38 (63%). Although positive genetic results were equally likely in malignant vs benign Pheo/PGL (76 vs 54%, p = 0.1), all 11 patients with germline SDHB mutations had malignant disease. In multivariable analysis, younger age, larger tumor size, and PGL were associated with malignancy (p < 0.05). Pheo patients with negative genetic testing and negative family history who developed metachronous metastases all had primary tumors ≥4 cm in size. Patients who are young, have larger tumors, positive genetic testing (especially SDHB) or have PGL require long-term follow-up. Patients with negative genetic testing or family history and Pheo <4 cm have a lower risk of malignancy, and de-escalated long-term surveillance may be appropriate follow-up.