Adults who have never married face significantly higher rates of cancer than their married, divorced, or widowed peers, according to a major new analysis of more than four million US cancer cases. The research suggests the social and lifestyle factors commonly associated with marriage play a far greater role in cancer risk than previously acknowledged.
The Scale of the Finding
Researchers from the University of Miami’s Sylvester Comprehensive Cancer Center, publishing their work in Cancer Research Communications, examined data from over 100 million people across 12 states between 2015 and 2022. They found the elevated risk for never-married individuals spanned nearly all major cancer types and was starkest for diseases linked to preventable causes like smoking, alcohol, and infection.
The magnitude of the increase was substantial. Never-married men were approximately 70% more likely to be diagnosed with cancer than married men. For never-married women, the risk was 85% higher than for their married counterparts.
Pronounced Risks for Specific Cancers
The disparity was particularly acute for certain cancers. Never-married men had about five times the rate of anal cancer. For never-married women, rates of cervical cancer were nearly triple those of married women. Both cancers are strongly associated with human papillomavirus (HPV) infection, highlighting the role of prevention and screening.
Significantly higher rates were also recorded for never-married adults in cancers of the liver and lung. For women, gynaecological cancers showed pronounced disparities, with never-married women facing 2.3 to 2.4 times the risk for ovarian and uterine cancers.
The study also revealed that the link between marital status and cancer risk strengthened with age, being more pronounced in adults over 50. This suggests the health effects of long-term lifestyle and social differences accumulate over decades.
A Complex Intersection with Race
When analysing race and marital status together, the researchers uncovered a notable pattern. Never-married Black men had the highest overall cancer rates of any group in the study. Yet, in a striking contrast, married Black men had lower cancer rates than married white men.
This finding, the researchers indicate, suggests marriage may be linked to particularly strong health benefits within the Black male demographic. It underscores the complex interplay between race, social structures, and health outcomes, where social determinants can contribute to up to 70% of cancer cases.
Why Marriage Correlates with Health
The study authors are emphatic that marriage itself is not a direct cancer preventative. Instead, marital status serves as a powerful marker for a cluster of social, behavioural, and economic advantages that influence long-term health.
Married individuals are statistically more likely to engage in healthier behaviours, such as smoking less, drinking less alcohol, and maintaining a better diet. They also tend to have greater financial stability, which facilitates access to healthcare and healthier living conditions.
Critically, marriage often provides a robust system of social support. A partner can help navigate the healthcare system, encourage attendance at regular checkups, ensure adherence to treatment plans, and provide critical support during illness. This network is linked to better health outcomes and even increased survival rates for cancer patients.
Conversely, loneliness and social isolation, which are more prevalent among never-married individuals, are associated with poorer health behaviours and lower engagement with healthcare services. By middle age, unmarried individuals may also experience more adverse physiological changes, such as increased inflammation.
For women, reproductive factors associated with marriage, like parity (having had children), are known to lower the risk of certain cancers such as ovarian and endometrial cancer.
Implications for Prevention and Screening
The research has clear implications for public health strategy and individual awareness. Dr. Frank Penedo, study author and associate director for population sciences at Sylvester, stated the findings point to the importance of targeting cancer risk awareness with attention to marital status.
“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,” Dr. Penedo said.
The study noted that cancers with robust screening programmes, like breast and prostate cancer, showed weaker associations with marital status. This underscores that regular screening can be a powerful equaliser, mitigating some health disparities linked to social factors.
Researchers acknowledge limitations, including that the study used legal marital status and did not capture cohabiting couples. Individual data on income or smoking were also not available, and a degree of selection bias—where healthier people may be more likely to marry—is possible. Nevertheless, the vast dataset provides compelling evidence that the social determinants woven into marital status are significant drivers of cancer risk across the population.