Bovine leukemia and breast cancer

According to a recent study, women who are infected with a virus called the bovine leukemia virus (BLV) might have an increased risk of breast cancer. Researchers tested breast tissue of 239 women for BLV and found that 59 per cent of those who had breast cancer also had BLV. Based on the study data and after taking other risk factors into consideration, the odds of having breast cancer were three times higher if BLV was present.

Cows with BLV rarely show any symptoms but is extremely common in the USA where almost all dairy herds test positive. Many dairy-containing products available in the UK come from the USA. The study authors say we need more evidence but it is probably transmitted to people through the consumption of cow’s body tissues (meat) or secretions (milk). 

Buehring et al. 2015. Exposure to Bovine Leukemia Virus Is Associated with Breast Cancer: A Case-Control Study. PLoS One.10 (9) e0134304.