Lifestyle Alone Cannot Explain Men’s Higher Cancer Risk

Cancer published a study showing that men have a higher cancer risk than women. This has long been known and largely attributed to lifestyle, such as smoking, alcohol consumption and a poorer diet. However, smoking, drinking and dietary factors do not appear sufficient to explain the difference in risk in this new study.

Why Do Men Develop Cancer More Often?

Researchers compared sex differences across 21 cancer types and found higher incidence in men for most cancers. For the most part, this greater susceptibility could not be explained by carcinogenic (cancer-causing) exposures. They suggest that the difference may reflect cancer-related biological differences between the sexes.

NOTE: In cancer, incidence means the number of newly occurring cases per 100 thousand people each year.

The study assessed behaviours, anthropometry (the measurement of the human body), lifestyles and medical histories to try to explain men’s higher cancer risk.

Study Details

Researchers analysed data from the National Institutes of Health-AARP Diet and Health Study (1995-2011). It included 171 thousand men and 122 thousand women. There were 26,693 cancer cases in total: 17,951 in men and 8742 in women.

Age-adjusted incidence of thyroid and gallbladder cancer was lower in men than in women. Anal cancer incidence was also similar between the groups.

Men had higher incidence than women for all other cancer types examined.

The largest differences to men’s disadvantage were seen in

• oesophageal adenocarcinoma,
• gastric cardia cancer and
• laryngeal (voice box) cancer.

After adjustment for demographic, lifestyle and dietary factors, these 3 cancers had the highest hazard ratios in men. Oesophageal adenocarcinoma risk was 10.8 times higher in men, compared with 3.5 times for laryngeal cancer and 3.4 times for gastric cardia cancer. Men still had lower thyroid and gallbladder cancer risk in this adjusted analysis.

The researchers said risk factors partly explained the greater incidence in men of oesophageal adenocarcinoma and liver, biliary tract, bladder, skin, colon, rectal and lung cancers. They also stated: “However, risk factors explained only a small proportion of the excess in men, ranging from 50% for lung cancer to 11% for oesophageal adenocarcinoma. ”

In conclusion, this study suggests that differences in cancer risk between men and women may reflect more than differences in carcinogen exposure, pointing to a potential role for sex-related biological mechanisms as a major determinant. The greater frequency of certain cancers in men is thought to arise from physiological, immunological, genetic, epigenetic and genomic mechanisms among a range of interconnected biological differences between the sexes.

The researchers recommend evaluating these mechanisms across cancer types worldwide to help determine why men have higher cancer incidence.