Marriage is linked to a lower risk of developing cancer, recent research found.

A study of more than 4 million cancer cases in the U.S. found that cancer rates were about 68% higher among men who have never married compared with those who have. For never-married women , the relationship was even more pronounced, with cancer rates roughly 83% higher, according to research published recently in the journal Cancer Research Communications.

Married people tend to have greater economic stability and better support systems, and they are more likely to stick with treatment, said Paulo Pinheiro, professor of cancer epidemiology at the University of Miami School of Medicine’s Sylvester Comprehensive Cancer Center and co-author of the findings.

Previous studies have found that married people who have cancer tend to get diagnosed earlier and have better survival rates.

The recent study looked at data collected between 2015 and 2022 encompassing more than 100 million people aged 30 or older from across 12 states. About 20% were unmarried.

The researchers compared cancer rates by marital status, and by sex and race. Some of the starkest findings involved preventable cancers linked to infections or behaviors like smoking   and drinking .

Unmarried men had five times the rate of anal cancer; unmarried women experienced three times the rate of cervical cancer. Both of these cancers are linked to the sexually transmitted infection HPV, or human papillomavirus, so the incidences may reflect differences in exposure and screening.

Married individuals tend to have healthier behaviors overall, including lower smoking and alcohol use, and more stable sexual and reproductive relationships, all of which are risk factors for cancer, Pinheiro said. They are also more likely to engage in preventive care.

Of course, the link doesn’t always hold true. “There are lots of marriages that are abusive and violent, and certainly they’re not going to contribute to any good outcomes,” Pinheiro added. “And then there are unmarried people with social support systems that will replace whatever beneficial effect marriage might be bringing to you.”

Ultimately, Pinheiro said he thinks the compromises that come with marriage—a partner telling another they’re smoking or drinking too much, or not sleeping or exercising enough , tend to lead to healthier outcomes.

“These kinds of micro-interventions can help after decades,” he said.

Write to Aylin Woodward at aylin.woodward@wsj.com