Clinical Course and Prognosis of Non-Secretory Multiple Myeloma

Objective: To determine the prognosis of patients with non-secretory myeloma. Methods: We studied 124 patients diagnosed with multiple myeloma who had no monoclonal protein detected on serum and urine immunofixation at diagnosis and on all subsequent follow up testing (non-secretory myeloma). The overall survival (OS) of patients with non-secretory myeloma was compared with 7075 patients with typical myeloma seen during the same time period in whom a monoclonal protein was detected at the time of diagnosis. Results: One hundred and twenty four patients met criteria for non-secretory multiple myeloma. The median follow-up was 102 months (range, 1-204 months). The median progression free survival with initial therapy was 28.6 months, and the median OS was 49.3 months. There was a significant improvement in OS since 2001; median survival 99.2 versus 43.8 months (prior to 2001) versus 99.2 months (2001-2012), P<0.001. OS was superior in patients with a normal baseline FLC ratio (n=10) compared to patients with an abnormal ratio (n=19), medians not reached in both groups. Prior to 2001, OS was similar in non-secretory myeloma (n=86) and secretory myeloma (n=4011), median 3.6 versus 3.5 years, respectively, P=0.63. However, among patients diagnosed between 2001-2012, OS was superior in non-secretory myeloma (n=36) compared to secretory myeloma (n=2942), median 8.3 versus 5.4 years, respectively, P=0.03. Conclusions: Non-secretory myeloma is an uncommon subtype of multiple myeloma. In the last decade, there has been an improvement in the survival of non-secretory myeloma, and appears superior to secretory myeloma.