Myeloma Of The Head: Is Palliative Radiation Worth It?

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Multiple myeloma (MM) of the head can present with central nervous system (CNS) involvement (brain metastases (BM) and/or leptomeningeal disease (LMD)), cranial neuropathies (CN) from base of skull (BOS) lesions, or pain. These groups may be referred for radiotherapy (RT), but prognosis and best RT management are unknown. We hypothesized CNS MM has worse clinical response and survival than compressive CN or pain. We screened RT courses delivered at our institution from 2008-2019 to find those associated with ICD-9/10 codes for plasma cell dyscrasias (203 or C90). We identified 49 delivered to the head for MM. Treatment groups were defined as 1) RT for LMD or BM, 2) RT for CN from BOS lesions not in group 1, and 3) RT for pain not in groups 1 or 2. We recorded clinicopathologic features for each patient as well as prior and concurrent therapies. Clinical responses (symptomatic and/or radiographic) were recorded categorically as progressive disease versus no, partial, or complete response. Logistic and multivariate regressions were run to identify factors predictive of clinical response and survival, respectively. Patient and treatment characteristics are shown in Table 1. 40/46 courses were evaluable for clinical response. Survival for group 1 trended worse, but clinical response and survival were no different between groups (p = 0.19 and 0.16, respectively). 16/18 patients treated for CN had at least partial response. Increased RT dose was the only significant predictor of clinical response on logistic regression (p = 0.008) and survival on linear regression (p = 0.042). Non-significant predictors were treatment group, age, number of prior lines of systemic therapy, history of prior stem cell transplant, presence of high-risk mutations, positive lumbar puncture, concurrent therapy (systemic or intrathecal), and prior progression to plasma cell leukemia. Survival and clinical response trended worse for MM of the CNS (LMD and BM), but good response rates for BOS lesions causing CN warrant RT consideration. Dose was the only significant factor associated with improved clinical response and survival. This retrospective study may be limited by small numbers and potential selection bias. Future collaborations will help elucidate the role of RT for these patients.Abstract 3768; TableGroupRT coursesMedian age (range)Median prior lines therapy (range)High-risk genetics* (positive/patients tested)Median dose (Gray) (range)Median survival (days) (range)Clinical Response (number of courses)ProgressionNo responsePartial responseComplete response11060 (41-69)7.5 (0-11)7/820.5 (4-30)79 (10-151)124021861 (45-82)4.5 (1-16)2/921 (9-40)160 (6-1640)0213331862 (43-74)6.5 (2-14)6/1422.5 (6-30)102 (8-1169)1374*high-risk mutations include t(4;14), t(14;16), t(14;20), del17p, and gain1q Open table in a new tab