People who have never married face a dramatically higher cancer risk than those who have ever been married, a major new U.S. study has found. Researchers analyzed more than 4.2 million cancer cases across 12 states from 2015 to 2022 and found that never-married men were 68% more likely to develop cancer, while never-married women faced an 83% higher risk.
The study, led by Paulo S. Pinheiro of the University of Miami School of Medicine, was published in Cancer Research Communications.
The findings challenge a long-held belief in health research that marriage benefits men far more than women. Researchers found the opposite to be true for cancer.
Never-married women showed consistently high risk across all racial and ethnic groups, while the picture for men varied more widely.
Pinheiro and his team say that this points to marriage being at least as important a social factor for women’s cancer risk as it is for men’s.
Marriage protects women from cancer just as much as men
The gap between never-married and ever-married adults grew larger with age, which researchers say suggests the benefits of marriage build gradually over a lifetime rather than appearing quickly.
Among adults under 55, the risk difference was smaller, likely because younger, never-married individuals may simply not have married yet, rather than having avoided it entirely.
Certain cancers showed far sharper differences than others. Anal cancer among men stood out the most, with never-married men facing a risk more than five times higher than ever-married men.
Researchers note this likely reflects higher rates of male-male sexual contact and HIV infection among never-married men. Cervical cancer showed nearly triple the risk among never-married women.
Lung, liver, esophageal, colorectal, and reproductive cancers also showed big differences, tied largely to smoking, alcohol use, infection exposure, and lower screening rates.
Cancer risk in never-married people accumulates over a lifetime
Prostate cancer offered an interesting detail. When researchers looked at cases caught through routine screening, the difference between never-married and ever-married men was relatively small.
But among men diagnosed with more advanced disease, the gap was much wider, suggesting that ever-married men benefit from earlier detection through regular medical care.
For liver cancer, the difference between never-married and ever-married adults was smaller among Asian and Pacific Islander populations.
Researchers explain this is because liver cancer in that group is largely caused by a virus passed from mother to child at birth, something that is not shaped by lifestyle or social factors in the same way.
Black men who marry show surprisingly lower cancer rates
Among Black men, never-married individuals had the highest cancer rates of any group in the study.
Yet married Black men actually had lower rates than married White men, a finding researchers say may reflect the fact that Black men who do marry face greater structural barriers to do so, making them a more health-stable group overall.
Researchers say marital status deserves a place in cancer prevention strategies, particularly as marriage rates continue to decline across the country.
