Long-term outcomes of 125 patients with metastatic pheochromocytoma or paraganglioma treated with 131I-mIBG.

Abstract

CONTEXT\nPrognosis of metastatic pheochromocytoma/paraganglioma following I-131-MIBG is incompletely characterized due to small samples and shorter follow-up in these rare, often indolent tumors.\n\n\nOBJECTIVE\nWe describe long-term survival, frequency and prognostic impact of imaging, biochemical and symptomatic response to I-131-MIBG.\n\n\nDESIGN\nRetrospective chart and imaging review at a tertiary referral center.\n\n\nPATIENTS\n668 person-years of follow-up in 125 patients with metastatic pheochromocytoma/paraganglioma with progression through prior multimodal treatment.\n\n\nINTERVENTION\nMedian 18,800 MBq I-131 MIBG.\n\n\nMAIN OUTCOME MEASURES\nOverall survival, RECIST 1.1 imaging response, symptomatic response per chart review and biochemical response (20% change over 2 consecutive assays of catecholamines, VMA, metanephrines or chromogranin A).\n\n\nRESULTS\nMedian survival from diagnosis was 11.5±2.4y; following metastasis, 6.5±0.8y; post treatment, 4.3±0.7y.Among n=88 with follow-up imaging, 1% experienced complete response, 33% partial response, 53% stability, 13% progression. 51% showed subsequent progression, median progression-free-survival 2.0±0.6y. Stability/response vs. progression at first imaging follow-up (3-6 months) predicted improved survival, 6.3 vs. 2.4 years (p=0.021).59% of n=54 patients demonstrated biochemical response. 50% of these relapsed, median time to laboratory progression 2.8±0.7y. Biochemical response did not predict extended survival.75% of n=83 patients reported improvement in pre-treatment symptoms, consisting primarily of pain (42%), fatigue (27%) and hypertension (14%). 61% of these experienced subsequent symptomatic progression at median 1.8±0.4y. Symptomatic response did not predict extended survival.\n\n\nCONCLUSIONS\nImaging, symptomatic and laboratory response to multimodal treatment including high dose 131 I-MIBG were achieved on long-term follow up in metastatic pheochromocytoma or paraganglioma. Imaging response at 3-6 months was prognostic.