Your love life could be affecting more than just your heart.
A sweeping new study compared people who are or have been married with those who’ve never tied the knot and found one group faces a much higher lifetime risk of cancer.
“It’s a clear and powerful signal that some individuals are at a greater risk,” Dr. Paulo Pinheiro, study co-author and a physician-scientist at the University of Miami’s Sylvester Comprehensive Cancer Center, said in a press release.
In the study, Pinheiro and his colleagues looked at more than 4 million cancer cases across a population of over 100 million people in 12 states between 2015 and 2022.
They focused on adults ages 30 and older, breaking down cancer rates by marital status, sex and race, while adjusting for age.
The participants fell into two camps: Those who were or had been married — including divorced and widowed people — and those who’d never said “I do.”
In all, about one in five adults in the study had never married.
The researchers found that this group faced “substantially higher rates” of developing cancer compared with those who were or had gotten hitched.
For cancers with robust screening programs, like breast, thyroid and prostate, the difference was smaller.
But for more preventable cancers tied to lifestyle factors, the disparities grew.
Think smoking, heavy drinking and sexually transmitted infections — all behaviors that raise cancer risk and tend to be lower among married people.
Case in point: Men who never took the plunge had about five times the rate of anal cancer compared with married men.
Women who never wed, meanwhile, faced nearly triple the rate of cervical cancer compared with women who were or had been married.
Both cancers are closely linked to HPV — a common STI that can now be largely prevented through vaccination.
Other factors may also be at play. Married women, for instance, often have more children — a factor known as “parity” — which can lower the risk of certain cancers like endometrial and ovarian.
The researchers said this may be linked to the greater financial and emotional stability often associated with marriage.
Notably, cancer risk varied by gender.
Never-married men were about 70% more likely to develop cancer than married men, while never-married women had an 85% higher risk compared with their married counterparts.
That flips the usual script, with past research showing that men men often reap bigger health benefits from marriage.
The patterns also shifted across different racial groups.
Never-married Black men, for example, had the highest overall cancer rates. However, married Black men had lower cancer rates than married white men — suggesting marriage may offer especially strong protective benefits in that demographic.
The findings highlight another advantage of marriage when it comes to cancer, with previous studies showing that married people tend to get diagnosed earlier and have better survival rates.
The researchers suggested this is likely because married people often, though not always, have stronger support systems, greater economic stability and are more likely to follow cancer treatment regimens.
But that doesn’t mean a wedding ring doubles as a shield against disease.
“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,” said Dr. Frank Penedo, associate director for population sciences and director of the Sylvester Survivorship and Supportive Care Institute.
“For prevention efforts, our findings point to the importance of targeting cancer risk awareness and prevention strategies with attention to marital status,” he added.
The study had some limits.
For one, people who smoke less, drink less, take better care of themselves and are more socially integrated may also be more likely to get married.
Even so, the researchers found that the link between marriage and cancer was strongest in adults over 50, suggesting that as people age and accumulate risk, being hitched — or having been hitched — might offer an edge.
“These findings suggest that social factors such as marital status may serve as important markers of cancer risk at the population level,” Pinheiro said.
The study also didn’t include unmarried people in committed relationships. Pinheiro said that group is probably small but worth keeping an eye on in future research.
Looking ahead, the team also hopes to track married, divorced and widowed adults over several decades to see how different marital statuses affects cancer risk.
“The association between marriage status and cancer risk is an interesting, new observation that deserves more research,” Pinheiro said.
The findings come as Americans are tying the knot less often, a tend that has persisted for decades.
In 2024, just 66% of Americans ages 15 and older have been married at least once, down from 85% in 1960, according to Census data.
