Researchers at the University of Miami analyzed more than 500 million person-years of SEER data across 12 states from 2015 to 2022 — one of the most comprehensive population-based analyses of marital status and cancer incidence in the United States to date. The finding was consistent and substantial: adults who had never married had significantly higher cancer incidence than those who had ever married (including married, divorced, separated, or widowed individuals) across nearly all major cancer sites, racial and ethnic groups, and age categories.
Never-married Black men had a cancer incidence rate of 1,600.6 per 100,000 — the highest of any demographic group in this study, and a figure that sits uneasily alongside how rarely marital status appears in cancer risk frameworks.
Overall, cancer incidence was 68% higher in never-married men and 83% higher in never-married women (incidence rate ratios [IRR] 1.68 and 1.85, respectively). Site-specific differences were even larger: IRRs reached 5.04 for anal cancer in men and 2.64 for cervical cancer in women. The largest gaps were observed for cancers linked to infections, tobacco, and alcohol use, while differences were smaller for cancers such as breast, thyroid, and prostate.
The associations strengthened with age, peaking at ages 70 to 74 years before attenuating slightly in older groups — a pattern the authors suggest may reflect cumulative social and behavioral exposures over the life course rather than biological differences alone.
These disparities were most pronounced among Black men. Notably, among ever-married men, Black men had lower cancer incidence than White men (752.6 vs. 836.2 per 100,000). The authors suggest this pattern may reflect selection into marriage: in populations facing structural barriers to marriage — including economic inequality and incarceration — those who do marry may represent a more health-selected group. This is a hypothesis rather than a direct finding, but it reframes what the observed differences may represent.
“Marital status is often treated as a background demographic variable. Yet, our findings suggest that it may function as a social exposure that captures dimensions of cancer risk not fully explained by race, age, or socioeconomic status,” the authors write.
The open question is one of mechanism and causation. Legal marital status is a blunt measure: it does not capture cohabitation, relationship quality, partnership duration, or sexual orientation. Long-term partners who never married are classified as never-married, while the “ever-married” group includes married, divorced, and widowed individuals. In addition, individual-level data on income, parity, smoking, and diet were not available — factors that likely lie along the causal pathway.
The strongest site-specific differences — particularly for HPV-related cancers and those associated with tobacco and alcohol — are consistent with differences in sexual behavior, exposure risks, and screening uptake, though these factors were not directly measured in the study.
With roughly 1 in 5 adults aged 30 and older in the study population classified as never-married — a proportion that has risen over time — the authors suggest that incorporating marital status into cancer surveillance and risk stratification frameworks may help identify at-risk populations more precisely.
The evidence remains associational, not causal. But the consistency, magnitude, and patterning of the findings suggest that marital status functions as a meaningful social indicator of cancer risk — one that may capture cumulative behavioral, social, and structural exposures not reflected in traditional clinical variables.
No conflicts of interest were disclosed.
Source: Cancer Research Communications
