Infertility and not fathering children are associated with an increased risk of breast cancer in men, according to a case-control study published in Breast Cancer Research.

The researchers noted that few studies have assessed the association between reproductive history and male breast cancer, owing to the rarity of the disease. However, reproductive-related factors are known to be important in female breast cancer etiology. 

“[A]lthough that relates to the hormonal consequences of parity, which could not plausibly apply in men, it nevertheless seems worth investigating whether male fertility relates to male breast cancer risk,” the researchers wrote. 


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To that end, the researchers evaluated data from 1998 men with invasive (92%) or in situ (8%) breast cancer diagnosed between 2005 and 2017. The researchers compared these cases to 1597 healthy male control individuals. The control individuals were either non-blood relatives of the cases or the husbands of women participating in a different study.

Male-origin infertility was associated with a significantly increased risk of developing breast cancer (odds ratio [OR], 2.03; 95% CI, 1.18-3.49; P =.01). Female-origin infertility was not associated with the risk of male breast cancer. 

When patients were stratified by tumor type, male-origin infertility was associated with a significantly increased risk of breast cancer among men with invasive disease but not breast cancer in situ. The researchers noted, however, that the sample size for in situ cases was small.

There was a significant increase in the risk of breast cancer among men who had not fathered any children (OR, 1.50; 95% CI, 1.21-1.86; P <.001).

Men who had 2 or more children had a significantly decreased risk of breast cancer. The OR was 0.60 (95% CI, 0.48-0.75; P <.001) for men with 2 children and 0.66 (95% CI, 0.52-0.84; P <.001) for men with 3 or more children. 

“[O]ur large case-control study gives strong evidence that male infertility is associated with raised risk of breast cancer in men,” the researchers concluded. “The reasons are uncertain and need to be investigated.”

Reference

Swerdlow AJ, Bruce C, Cooke R, Coulson P, Jones ME. Infertility and risk of breast cancer in men: A national case-control study in England and Wales. Breast Cancer Res. Published online May 17, 2022. doi:10.1186/s13058-022-01517-z

This article originally appeared on Cancer Therapy Advisor