Abstract

BACKGROUND: Malignant pheochromocytoma and paraganglioma (mPPGL) are not so common and the factors predicting the metastatic behavior are not well understood.

METHODS: This retrospective cohort study included 218 patients with PPGL managed at our center over a period of 11 years (2013-2024). The clinical profile and treatment outcomes of patients with mPPGL were studied and were compared with non-metastatic PPGL(non-mPPGL).

RESULTS: Thirty-six patients had mPPGL and the median age at diagnosis of metastases was 39.5 years(range 10-62). Twenty-one(58.3%) patients had synchronous metastases and 15(41.7%) developed metachronous metastases after a median duration of 76 months(range 13-270 months) from the diagnosis of the primary tumor. Metastases were detected in 100% of patients who had 18FDG(4/4) and 68 Ga DOTATATE(4/4) PET-CT, 97.2% (35/36) with CT/MRI and 79.3%(23/29) with 131I MIBG scan. Surgery was the primary treatment in 78%, and 131I MIBG therapy was administered to 19(52.8%) patients. Eleven patients succumbed due to metastatic disease and among them nine died within a year of diagnosis of metastases, the median survival at last follow-up was 31.5 months (range 3-96). On comparing mPPGL(n = 36) and non-mPPGL(n = 182), we found that patients with mPPGL had larger tumors (8.8 ± 5.2 vs. 6.3 ± 3.3, p = 0.001), had less frequent adrenergic symptoms and more often had extra-adrenal tumors.

CONCLUSION: Malignant PPGLs had a variable clinical course and were amenable to multimodal therapeutic strategies with a favorable outcome in about 67% of the patients. Although mPPGL had larger tumor diameter compared to non-mPPGL, no particular size cut-off could accurately predict metastases. Adjuvant 131I MIBG therapy is a useful treatment option in resource limited settings.