Drugs for ovarian tumor can treat breast cancer

The most comprehensive analysis yet of breast cancer has revealed that one of the most deadly subtypes is genetically more similar to ovarian tumors than to other breast cancers.

The findings suggest that most basal-like breast tumors and ovarian tumors have similar genetic origins and potentially could be treated with the same drugs, said the study's co-leader Matthew J. Ellis, MD, PhD, the Anheuser-Busch Chair in Medical Oncology at Washington University School of Medicine in St. Louis.

Basal-like tumors account for about 10 per cent of all breast cancers and disproportionately affect younger women and those who are African-American.

The new research is part of The Cancer Genome Atlas project, which brings together leading genetic sequencing centers, including The Genome Institute at Washington University, to identify and catalog mutations involved in many common cancers. The effort is funded by the National Institutes of Health (NIH).

"With this study, we're one giant step closer to understanding the genetic origins of the four major subtypes of breast cancer," said Ellis, who treats breast cancer patients at the Siteman Cancer Center at Barnes-Jewish Hospital and Washington University.

"Now, we can investigate which drugs work best for patients based on the genetic profiles of their tumors. For basal-like breast tumors, it's clear they are genetically more similar to ovarian tumors than to other breast cancers. Whether they can be treated the same way is an intriguing possibility that needs to be explored," he added.

Hormone therapy for ovarian cancer

Hormone therapy is the use of hormones or hormone-blocking drugs to fight cancer. This type of systemic therapy is rarely used to treat epithelial ovarian cancer, but is more often used to treat ovarian stromal tumors.

Gonadotropin-releasing hormone (GNRH) agonists switch off estrogen production by the ovaries. These drugs are useful in lowering estrogen levels in women who are premenopausal. Examples of GNRH agonists include goserelin (Zoladex®) and leuprolide (Lupron®). These drugs are injected every 1 to 3 months. Side effects can include any of the symptoms of menopause, such as hot flashes and vaginal dryness. If they are taken for a long time (years), these drugs can weaken bones (sometimes leading to osteoporosis).

Tamoxifen is an anti-estrogen drug that is often used to treat breast cancer. It can also be used to treat ovarian stromal tumors and is rarely used to treat advanced epithelial ovarian cancer. The goal of tamoxifen therapy is to prevent any estrogens circulating in the woman’s body from stimulating growth of the cancer cells. Even though tamoxifen may prevent estrogen from nourishing the cancer cells, it acts like a weak estrogen in other areas of the body. It does not cause bone loss, but can cause hot flashes and vaginal dryness. People taking tamoxifen also have an increased risk of serious blood clots in the legs.