Session: FP29-Adrenal Tumors & Pheochromocytoma
Room 134 (Moscone Center)
Poster Board MON-37
We performed a retrospective analysis of the case records of patients with metastatic phaeo/PGL who received 131I-MIBG and were followed up according to a defined protocol between 1986 and 2011. In brief, patients (if possible) had repeat hormonal evaluation (24h urinary catecholamines/metanephrines) and imaging within 6 months of 131I-MIBG therapy.
Twenty two patients (9 male, mean age 43.4y) were identified, 12 with metastatic PGL and 10 with phaeo. In total, 68 doses of 131I-MIBG were administered with an average dose of 9835 MBq. Twenty three per cent of subjects were found to be positive for the succinate dehydrogenase B gene (SDHB), 23% had no genetic mutation identified and 54% were not tested for a genetic mutation (although 5 subjects exceeded the maximum age above which genetic testing is not routinely performed).
Symptomatic, biochemical and tumour responses to 131I-MIBG were classified as: complete resolution, stable disease (no change or <25% increase in tumour size /catecholamine excretion rate), progressive disease (>25% increase in tumour size/catecholamine excretion rate) partial response (>50% increase in tumour size/catecholamine excretion rate).
The outcome at 6 months after the first dose of 131I-MIBG are summarised below:
- Complete resolution: symptoms 5%, biochemical 5%, tumour 5%
- Stable disease: symptoms 59%, biochemical 50%, tumour 59%
- Progressive disease: symptoms 9%, biochemical 9%, tumour 9%
- Partial response: symptoms 18%, biochemical 5%, tumour 14%
- Unknown: symptoms 9%, biochemical 32%, tumour 14%
In general, 131I-MIBG was well tolerated; 50% of subjects reported no adverse effects, 32% described nausea and vomiting and 23% developed transient bone marrow defects. No severe adverse events directly related to 131I-MIBG were reported. One year survival was 77%.
131I-MIBG is safe and associates with disease stabilisation or improvement in the majority of patients with metastatic phaeo/PGL. Lack of an alternative ‘gold standard’ treatment and the rarity of this condition make randomised, placebo controlled or direct comparator studies extremely challenging.
Nothing to Disclose: MR, AR, TMY, NR, CGP, EMF
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