Metastatic Disease in Phaeochromocytomas and Paragangliomas in Various Genotypes-A Systematic Review and Meta-analysis.

Paragangliomas and phaeochromocytomas (PPGLs) are rare neuroendocrine tumours with 10% to 20% of patients developing metastatic disease. The tumors exhibit a high degree of heritability, and pathogenic genetic variants have been associated with metastases. We aimed to investigate the association between the genotype of PPGL patients and their risk of metastatic disease, adjusting for time. A systematic search was conducted in PubMed and Embase. The primary outcome was the rate of metastatic disease per 100 followed patient-years analyzed through meta-analyses. A significantly increased rate of metastatic disease per 100 followed patient-years was observed in all pathogenic germline variants included in the analyses, compared to the group with no identified variant. The group with no variant had a rate of 1.55 per 100 patient-years. SDHA, SDHC, SDHD, VHL, RET, NF1, and MAX had rates of 13.73, 6.27, 2.03, 2.34, 1.91, 4.11, and 9.66, respectively. The rate of SDHB is not presented as statistical heterogeneity exceeded 75%. The pathogenic somatic variant EPAS1 showed a rate of 3.82. Cluster-divided meta-analyses resulted in rates of 4.41 and 3.0 for cluster 1 and cluster 2, respectively. Meta-regression analysis revealed a 2.3-fold higher rate for the SDHB variant compared to the other cluster 1 variants. We present associations between genotype and metastatic disease in PPGL patients. Our results indicate that patients harboring a pathogenic genetic variant have a higher rate of metastases compared to patients with no identified variant. High heterogeneity in several analyses suggests that further large cohort studies are needed.