Multiple myeloma incidence, mortality, and survival differences at the intersection of sex, age, and race/ethnicity: A comparison between Puerto Rico and the United States SEER population

Background: Multiple myeloma (MM) survival has increased during the last decades due to the introduction of new therapies. We investigated the intersectionality among age, sex, and race/ethnicity to better understand the pattern of MM incidence, mortality, and survival. Methods: Puerto Rico (PR) Central Cancer Registry and the United States of America (US) Surveillance, Epidemiology, and End Results (SEER) Program databases were used. We analyzed MM incidence and mortality trends from 2001 to 2019 using Joinpoint regression models to calculate annual percent change (APC). Agestandardized rate ratios (SRR) for incidence and mortality were used to compare PR with US SEER racial/ ethnic groups during 2015-2019. Five-year survival analyses were also performed stratified by age and sex. Results: Regardless of age and race/ethnicity, males had higher MM incidence and mortality rates than females. PR had a higher increase in incidence rates of MM than other ethnic groups, regardless of sex and age (PR APC = 4.3 among males <65, 3.1 among males >= 65, 6.3 among females <65, and 2.6 among females >= 65 years old). No significant change in mortality APCs (p > 0.05) was observed in PR when stratified by age or sex while other groups showed a decrease. Among males < 65 years, PR had significantly higher incidence rates than nonHispanic Whites (NHW), and US Hispanics (USH). However, among both males and females >= 65 years, PR had significantly lower MM mortality rates than NHW, non -Hispanic Blacks (NHB), USH, and US Overall. In terms of survival, PR showed the lowest 5 -year overall survival among males < 65 years (54.6%, 95% CI: 47.2-61.5) and males >= 65 years (34.5%, 95% CI: 29.2-39.9) but not among females. Conclusion: The incidence of MM in PR increased significantly over the study period, particularly among younger women. Despite the introduction of new therapies, mortality rates in PR have remained stable while other ethnic groups show significant decreases among all intersections of sex and age.