Incidence of spinal disease and role of spinal radiotherapy in multiple myeloma.

Background: Spinal disease (spd) in multiple myeloma (mm) can be a major source of morbidity in newly diagnosed patients and long-term survivors. We retrospectively assessed the incidence of spinal disease in patients newly diagnosed with myeloma, its effect on survival, and the possible effect of spinal radiation therapy (rt). Methods: Patients diagnosed with mm between 2010 and 2014 were identified through the provincial cancer registry. Plain radiography, computed tomography, and magnetic resonance imaging were reviewed to detect and document the type of spd. Data related to rt and systemic therapy were collected. Kaplan-Meier and time-varying Cox regression models were used to describe overall survival. Results: Of 306 identified patients with newly diagnosed mm, 51% had spd, including 17% with lytic disease, 68% with compression fractures, and 15% with spinal cord compression. Of the patients with spd, 61% received spinal rt. Of those patients, 84% received spinal rt within 3 months after their diagnosis. Median dose was 20 Gy. Most patients (89.2%) received chemotherapy, and 22.5% underwent autologous stem-cell transplantation. Only 6 of the patients treated with spinal rt received re-irradiation to the same site. Overall survival was similar for patients with and without spd. On multivariate analysis, spinal rt had no effect on survival. Conclusions: In patients newly diagnosed with mm, spd is a common presentation. With current systemic therapy, the presence of spd had no adverse effect on overall survival. The effect of spinal rt on overall survival was nonsignificant.