It’s just possible that we could be giving girls a dose of protection against breast cancer without even knowing it. That’s the intriguing possibility raised by cutting-edge research on the human papillomavirus (HPV) vaccine (Gardasil), currently available for girls and young women between the ages of 9 and 26. HPV has been shown to cause cervical cancer.

A new study from Australia suggests that HPV may also cause some forms of breast cancer. The study found high-risk strains of HPV in roughly one-third of cancerous breast cells. Similar findings have been reported in breast cancer samples from all over the world, says James Lawson, M.D., one of the authors of the study. But his group used a more sensitive technique which provides “unambiguous evidence” of HPV in both “ductal carcinoma in situ” (DCIS) and “invasive ductal carcinoma” (IDC) breast cancers. The study, published in the British Journal of Cancer, suggests that “HPV may have a causal role in many breast cancers.”

So could the HPV vaccine provide “two-for-one” protection? “It’s interesting and it may well be true, but we have to be very careful because it’s still very preliminary data,” comments breast cancer expert Susan Love, M.D., president of the Dr. Susan Love Research Foundation

Still, Love says given that “80 percent of young women who get breast cancer have no risk factors whatsoever, and we have no clue what’s causing it,” the idea of a viral cause and vaccine is “something to follow with interest and something to broaden how we think about cancer.”

Another intriguing possibility: Since the Australian study found HPV in a few samples of healthy breast tissue, it may be possible that the presence of the virus is an early warning sign for cancer that is just starting to develop—sort of like a Pap smear for breast cancer. As for the HPV vaccine, it’s nice to know that the HPV vaccine given to girls and young women might provide even more protection than previously believed, but that’s not enough reason to go out and get the shot if you haven’t already been vaccinated, says Love. All vaccines have some risks that have to be considered and weighted against the benefits.