Trends in cause of death among patients with multiple myeloma in Puerto Rico and the United States SEER population, 1987-2013

Multiple myeloma (MM) survival has improved due to recent developments in MM treatment. As a result, other co-morbid conditions may be of increasing importance to MM patients' long-term survival. This study examines trends in common causes of death among patients with MM in Puerto Rico, and in the US Surveillance, Epidemiology, and End Results (SEER) population. We analyzed the primary cause of death among incident MM cases recorded in the Puerto Rico Central Cancer Registry (n = 3,018) and the US SEER Program (n = 67,733) between 1987 and 2013. We calculated the cumulative incidence of death due to the eight most common causes and analyzed temporal trends in mortality rates using joinpoint regression. Analyses of SEER were also stratified by Hispanic ethnicity. MM accounted for approximately 72% of all reported deaths among persons diagnosed with MM in Puerto Rico and in SEER. In both populations, the proportion of patients who died from MM decreased with increasing time since diagnosis. Age-standardized temporal trends showed a decreased MM-specific mortality rate among US SEER (annual percent change [APC] = -5.0) and Puerto Rican (APC = -1.8) patients during the study period, and particularly after 2003 in non-Hispanic SEER patients. Temporal decline in non-MM causes of death was also observed among US SEER (APC = -2.1) and Puerto Rican (APC = -0.1) populations. MM-specific mortality decreased, yet remained the predominant cause of death for individuals diagnosed with MM over a 26-year period. The most pronounced decreases in MM-specific death occurred after 2003, which suggests a possible influence of more recently developed MM therapies.