Married adults less likely to get cancer than those who are single: study

A marriage official offers a couple their rings during their wedding in New York, Wednesday, Feb. 14, 2007. THE CANADIAN PRESS/AP-Bebeto Matthews

A study suggests that marital status may play a role in your risk of developing cancer, with people who have never married facing higher rates of the disease.

Published last month in the Cancer Research Communications, the study examined data from more than 500 million person-years across 12 U.S. states between 2015 and 2022.

Person-years is a unit of measurement combining the number of people in a study with the time each person is observed.

Researchers examined cancer incidence among adults aged 30 and older, comparing those who had never married with individuals who were currently or previously married.

The findings found that never-married men had a 68 per cent higher chance of developing cancer, while never-married women had an 83 per cent higher rate of incidence compared, to their ever-married counterparts.

Lead author Paul Pinheiro told CTVNews.ca in an email the associations appeared stronger in women because reproductive cancers, such as endometrial and ovarian cancer, are “naturally more common among never-married women, because marital status is historically associated with parity and reproductive patterns at the population level.”

These differences were observed across nearly all major cancer types, demographic groups and age categories.

Importantly, the gap was especially pronounced for cancers linked to preventable risk factors. For example, cancers associated with smoking, alcohol use and infections — such as anal and cervical cancers — showed some of the largest disparities.

When asked what this suggests about prevention and health-care access, Pinheiro explained that cancer prevention is “strongly shaped by social and behavioral environments.”

He said this includes health behaviors, vaccination uptake, preventive care, and health-care engagement that may all be influenced by social support systems and life circumstances.

“The findings suggest that certain socially less-supported populations may benefit from more proactive prevention and outreach efforts,” Pinheiro explained.

In men, rates of anal cancer were more than five times higher among those who had never married, while women who had never married faced nearly triple the rate of cervical cancer.

By contrast, cancers less influenced by behaviour or screen — such as prostate, breast and thyroid cancers — showed smaller differences between marital groups.

Why marriage?

“This study was motivated by a broader question in cancer epidemiology: whether social relationships and social support are reflected in cancer risk at the population level,” Pinheiro said.

“Marital status is an imperfect, but widely available marker of social connection, household support and life circumstances,” Pinheiro added.

Researchers caution that marriage itself is unlikely to directly prevent cancer. Instead, marital status appears to function as a broader social indicator tied to lifestyle, access to health care and long-term support systems.

Married individuals often benefit from shared economic resources, emotional support and encouragement to seek preventive care, all of which can influence cancer risk over time, the study said.

“Married partners may also influence everyday health habits in simple ways, such as encouraging someone to smoke or drink less, eat better, go for walks, see a doctor, or stay engaged with preventive care,” Pinheiro said.

Age also played a key role. The study found that differences in cancer risk were more pronounced among adults aged 55 and older, suggesting the effects of social and behavioural patterns accumulate over the life course.

The finding also revealed disparities across racial and ethnic groups. Never-married Black men experienced the highest cancer incidence overall, while patterns varied among other groups.

The study said these differences highlight how structural inequalities such as access to health care and socio-economic resource interact with martial status to shape health outcomes.

Despite the strong associations, the researchers stress that the study does not imply that people should marry to reduce cancer risk.

Instead, the authors of the study said it underscores the importance of addressing the underlying factors that marriage may represent. Individuals who have never married may be more likely to experience social isolation, engage in higher-risk behaviours or have less access to preventive health care — all of which can contribute to increased cancer risk.

Future work

The study also acknowledges its limitations. It does not account for unmarried individuals in long-term partnerships, nor can it fully separate the effects of “selection” — the idea that healthier individuals may be more likely to marry — from the potential benefits of marriage itself.

Pinheiro also said the study did not account for different categories of ever-married individuals, such as those presently married, divorced, separated or widowed populations over time.

“We did not have information on cohabitation or on same-sex versus opposite-sex marriages and relationships,” Pinheiro identified.

Researchers say public health strategies may need to adapt accordingly, based on their findings.

Rather than focusing on martial status alone, Pinheiro emphasized the importance of strengthening social support networks, improving access to screening and promoting healthy behaviours across all populations.

“Our study did not include individual-level screening histories or health-care utilization data, so these questions will require further investigation,” Pinheiro said.

“In any case, when it comes to cancer prevention, screening is not the entire story. A substantial part of cancer risk is shaped by underlying health behaviors and baseline risk-factor exposures,” he added.

The study suggests the message is less about marriage itself and more about the broader social conditions that may influence health.