One type of breast cancer shares genetic features with a serious form of ovarian cancer, a new study has found, and researchers say the discovery could mean both diseases could be treated with the same drugs.

Researchers with the National Cancer Institute and National Human Genome Research Institute in the US examined data from The Cancer Genome Atlas and confirmed that there are four main subtypes of breast cancer, each of which has its own biology and survival prospects.

One of these subtypes, basal-like breast cancer, has marked genomic similarities to ovarian cancer, and the study found that both might be susceptible to chemotherapy drugs such as cisplatin and other compounds that target DNA repair, as well as agents that inhibit the growth of blood vessels, cutting off blood supply to the tumour.

"The molecular similarity of one of the principal subtypes of breast cancer to that found in ovarian cancer gives us additional leverage to compare treatments and outcomes across these two cancers," Dr. Harold Varmus said in a press release. "This treasure trove of genetic information will need to be examined in great detail to identify how we can use it functionally and clinically."

Study co-leader Matthew J. Ellis said the discovery suggests basal-like breast cancers could be treated more effectively if they're approached like ovarian cancers and not other breast cancers.

"With this study, we're one giant step closer to understanding the genetic origins of the four major subtypes of breast cancer," he said. "Now, we can investigate which drugs work best for patients based on the genetic profiles of their tumours. For basal-like breast tumours, it's clear they are genetically more similar to ovarian tumours than to other breast cancers. Whether they can be treated the same way is an intriguing possibility that needs to be explored."

The findings were published online Sunday in the journal Nature.