According to a new study, the risk of invasive breast cancer in men may be associated with self-reported infertility in the male partner. The findings of the research were published in an open-access journal 'Breast Cancer Research'. Breast cancer in males is less common than in females and its relation to infertility has only been investigated in small studies to date. Only one small study has suggested a possible association between men fathering children and breast cancer. The authors interviewed 1,998 males in England and Wales diagnosed with breast cancer, with 112 (5.6 per cent) also self-reporting infertility and 383 (19.2 per cent) having no children. Authors from The Institute of Cancer Research (London, UK) investigated the potential relationship between self-reported infertility or having had no children and the risk of breast cancer in men. Michael Jones and colleagues interviewed 1,998 males (under 80 years old) who were diagnosed with breast cancer between 2005 and 2017 and were living in England and Wales. They were compared with 1,597 males as a control group, who were not blood relatives. 80 males reported infertility (5.0 per cent) in the control group. The risk of invasive breast cancer tumours (cancerous cells that spread beyond where they first formed) was significantly associated with male infertility based on 47 individuals with breast cancer (2.6 per cent) compared to 22 controls without cancer but with self-reported infertility (1.4 per cent). The authors did not find any significant associations between the risk of breast cancer and a partner's infertility or when the source of infertility was not known.