Adults who have never married are significantly more likely to develop cancer than those who have been married at some point in their lives, a new study from the University of Miami's Sylvester Comprehensive Cancer Center suggests.
The population-based data suggests the gap in cancer risk was surprising, researchers said. Never-married men were about 68 percent more likely to develop cancer than their married counterparts. The disparity was even wider for women: those who had never married were approximately 85 percent more likely to receive a cancer diagnosis than women who were or had previously been married.
For certain cancer types, the differences were even larger. Never-married men developed anal cancer at roughly five times the rate of men who had married. Never-married women had nearly three times the rate of cervical cancer compared with women who had married. Both cancers are strongly tied to HPV infection, and researchers said the disparities likely reflect differences in exposure to the virus, as well as gaps in screening and prevention.
Researchers focused on malignant cancers diagnosed in adults 30 and older and divided participants into two groups: those who had never married and those who were currently or had previously been married, including divorced and widowed individuals. About one in five adults in the dataset had never married.
The research was led by Paulo Pinheiro, a professor of cancer epidemiology at the University of Miami Miller School of Medicine's Department of Public Health Sciences. He said the scope of the findings took him by surprise.
"Marriage as a protective factor in cancer risk has been largely ignored so far, and this is the first study," Pinheiro said. "With the prevalence of marriage decreasing in the U.S., this is something that should be further studied."
Racial disparities also emerged in the data. Never-married black men had the highest overall cancer rates of any group examined. However, once married, black men actually had lower cancer rates than married white men. This pattern, researchers said, underscores just how protective marriage appears to be within that population—as this population faces more structural barriers to marriage—meaning those who do marry represent a more health-stable group.
For cancers tied to smoking, alcohol use, and reproductive history—such as lung, esophageal, ovarian, and endometrial cancers—the correlation between never-married status and higher risk was the strongest. In contrast, cancers with robust screening programs, including breast, prostate, and thyroid cancers, showed weaker links to marital status.
Researchers were careful to note that the findings should not be read as a prescription to marry.
"It means that if you're not married, you should be paying extra attention to cancer risk factors, getting any screenings you may need and staying up to date on health care," Penedo said. "For prevention efforts, our findings point to the importance of targeting cancer risk awareness and prevention strategies with attention to marital status."
"These findings suggest that social factors such as marital status may serve as important markers of cancer risk at the population level," Pinheiro said.
Researchers acknowledged they could not account for individuals in long-term committed partnerships who were not legally married, nor did they have individual-level data on income, education, or health behaviors. Future research, the authors said, should track people for decades to better understand how changes in marital status over a lifetime affect cancer risk.
"But the association between marriage status and cancer risk is an interesting, new observation that deserves more research," Pinheiro said.