FP29-5 Treatment of metastatic phaeochromocytoma and paraganglioma with 131I- meta-iodobenzylguanidine (131I-MIBG) - the experience of a tertiary referral centre

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: FP29-Adrenal Tumors & Pheochromocytoma
Monday, June 17, 2013: 10:45 AM-11:15 AM
Presentation Start Time: 11:05 AM
Room 134 (Moscone Center)

Poster Board MON-37
Matthew Rutherford1, Alastair Rankin1, T. Michael Yates1, Nicholas Reed2, Colin Graham Perry1 and E. Marie Freel*3
1Western Infirmary, Glasgow, United Kingdom, 2Beatson Oncology Centre, Glasgow, United Kingdom, 3Univ of Glasgow, Glasgow, United Kingdom
Phaeochromocytoma (phaeo) and paraganglioma (PGL) are rare conditions which are malignant in 10% of cases. Optimal treatment of non-resectable, malignant Phaeo/PGL is controversial but, in patients with131I-MIBG avid tumours, we routinely offer 131I-MIBG therapy in an attempt to slow disease progression. This abstract summarises the response and tolerability of this therapy in a cohort of patients treated in our department from 1986 to 2011.

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

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm