Adults who have never married are significantly more likely to develop cancer compared with those who are married or previously married, according to a major new study conducted by researchers at the University of Miami.
The researchers analysed more than four million cancer cases recorded across 12 states in the United States between 2015 and 2022. Their findings revealed that cancer incidence rates were 68% higher among never-married men and 85% higher among never-married women compared with individuals who were or had been married.
However, scientists stressed that marriage itself does not directly protect against cancer. Instead, the differences appear to be linked to lifestyle patterns, healthcare access, and social behaviours associated with relationship status.
Lifestyle And Social Factors Likely Drive The Risk
Clinical psychologist Frank Penedo, one of the study’s authors, emphasised the importance of proactive health care for those who are unmarried.
“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,” he said.
Researchers pointed out that several known cancer risk factors — including smoking, chronic stress, and reproductive history — are often associated with marital status. There is also a possibility that healthier individuals may be more likely to marry, which could partly explain the findings.
For the purposes of the research, unmarried couples living together were classified as single.
Sharp Differences Seen In HPV-Linked Cancers
Some of the most striking differences were observed in cancers linked to the Human Papillomavirus (HPV).
According to the study:
- Never-married men developed anal cancer at nearly five times the rate of married or previously married men.
- Never-married women were almost three times more likely to develop cervical cancer compared to married counterparts.
Researchers suggested that having a partner who encourages regular medical check-ups and screenings may contribute to earlier detection of certain cancers.
For cancers with well-established screening programmes — such as breast and prostate cancer — the difference between married and unmarried individuals was found to be much smaller.
Study Limitations Highlight Need For Further Research
The research was observational and did not track individual participants over time, meaning it could identify associations but not direct causes.
Additionally, all married or previously married individuals were grouped together regardless of the duration or quality of their relationships, which could influence results.
Epidemiologist Paulo Pinheiro said the findings suggest social circumstances should be considered when planning cancer prevention and screening strategies at a population level.
Marriage Not Always Healthier, Other Studies Show
While the study highlights increased cancer risk among never-married individuals, experts noted that relationship status alone does not determine overall health.
Other research has identified certain benefits linked to single life, such as stronger social networks beyond a partner and greater personal independence. Separate studies have also associated marriage with an increased risk of conditions such as Dementia.
These findings underline that health outcomes are influenced by multiple factors, including lifestyle, support systems, and healthcare habits — rather than marital status alone.