Human Papillomavirus (HPV) is the leading cause of cervical cancer, accounting for up to 95% of all cases. But a new study in the British Journal of Cancer suggests that vaccinating against it may also prevent against certain forms of breast cancer, which could save thousands of women’s lives every year.

They found evidence of HPV in 39% of ductal carcinoma samples and in 21% of the invasive ductal carcinoma samples they analyzed.

James Lawson and his colleagues at the University of New South Wales tested samples of cancerous breast tissue cells for the presence of the virus using a method that identifies specific genes in the virus. They found evidence of HPV in 39% of ductal carcinoma samples and in 21% of the invasive ductal carcinoma samples they analyzed. These cancers can be deadly because they have the potential to metastasize to other parts of the body, and they account for 70−80% of all breast cancers.

Co−author of the study, Noel Whitaker, says that the “finding that high risk HPV is present in a significant number of breast cancers indicates they may have a causal role in many breast cancers." He adds that "[c]onfirming a cancer−causing role for HPV in some breast cancers establishes the possibility of preventing some breast cancers by vaccination against HPV.”

Though other studies from around the world have also found a connection between HPV and breast cancer, some have been criticized for the methods used and the fact that they have often led to mixed results (with some studies reporting the incidence of HPV−positive cells to be as low as 4% and others as up to 86%).

However, the researchers of the current study used a slightly different technique – one which cuts down on specimen contamination and provides specific genetic evidence that the virus is present in the breast cancer cell. They also “double−checked” their methods by searching for characteristic changes in the infected cell, like an enlarged nucleus surrounded by a “halo,” which have been previously associated with HPV infection. The researchers say that they are looking further into techniques that will allow for faster, less expensive testing for the virus’ presence.