Marriage and Cancer Risk: A Contemporary Population-Based Study Across Demographic Groups and Cancer Types

Marriage is consistently associated with earlier cancer diagnosis and improved survival, but its relationship to cancer incidence is less understood. We examined cancer risk by marital status across cancer sites, sex, race/ethnicity, and age using large-scale, population-based US data. We analyzed Surveillance, Epidemiology, and End Results data from 12 states for adults ages ≥30 years, with denominators from the American Community Survey (2015-2022). Age-adjusted incidence rates were calculated, and negative binomial regression estimated incidence rate ratios (IRR) comparing never-married with ever-married adults, stratified by sex, age group, and cancer site. Never-married adults had higher cancer incidence [IRR = 1.68; 95% confidence interval (CI), 1.53-1.84 in men; 1.85; 95% CI, 1.68-2.03 in women] across nearly all major cancer sites and racial/ethnic groups (IRR range: 1.62 in White men to 1.96 in Black men). Never-married Black men had the highest incidence; among ever-married men, Black men had lower rates than White men. Among men, site-specific IRRs reached 5.04 for anal cancer; among women, 2.64 for cervical cancer. Pronounced marital disparities were observed for gynecologic cancers and for cancers linked to infections, tobacco, and alcohol, whereas differences were smaller for breast, thyroid, and prostate cancers. Ever-married adults consistently showed lower cancer risk. Whereas some variation may reflect selection into marriage, the magnitude and site-specific patterns of association suggest that marital status stratifies cancer risk through cumulative social and behavioral pathways, including those relevant to infection-related and lifestyle-associated cancers. SIGNIFICANCE: Ever-married status may serve as a useful social indicator for cancer risk stratification and prevention.