Background: Carriers of germline succinate dehydrogenase mutations (SDH) need life-long surveillance for the possible development of phaeochromocytomas and paragangliomas. However, there is no consensus about appropriate surveillance strategies. The aim of this study was to describe the long-term outcomes of a cohort of SDH carriers followed in our clinic.
Method: 49 patients were included in this study, 12 were index cases (9 SDHB, 3 SDHD) and 37 were mutation-positive asymptomatic carriers (22 SDHB, 9 SDHD and 6 SDHC). Patients were followed for a mean of 4.4 years (range 1-10). All patients are recommended to undergo biennial MRI imaging of neck/thorax/abdomen/pelvis, annual clinic review and plasma or urine metanephrine testing.
Results: 16 paragangliomas (10 SDHB, 6 SDHD) and 1 renal cell carcinoma (SDHB) and no phaeochromocytomas occurred in the 12 index cases (9 SDHB, 3 SDHD). Two index patients with paragangliomas (one abdominal, one head and neck) had widespread metastases on the initial scan. One SDHB and one SDHD index patient developed additional tumours during surveillance. Among the asymptomatic carriers, a total of 23 paragangliomas (22 SDHD and 1 SDHC) were detected in 8 (16%) patients (7 SDHD, 1 SDHC). Of these, 15 were detected on the first surveillance scan (14 SDHD, 1 SDHC) and 8 (all SDHD) were detected on subsequent scans. One patient (SDHD) developed a liver metastasis during surveillance. Of the seven SDHD carriers who had tumours on initial surveillance scan, six had the c.274G>T exon mutation. Average change in tumour size in those undergoing watchful surveillance was -0.12mm/year (range -4mm/year to +2mm/year). Adherence was suboptimal, only 45% of patients attended annual clinic visits, 67% underwent biennial MRIs and 45% had yearly metanephrine testing.
Conclusion: Biennial MRI scans appear to be an effective surveillance strategy in the long-term follow up of patients with SDH mutations.