The HIV protease inhibitor, Nelfinavir, can be used to treat HER2-positive breast cancer in the same capacity and dosage regimen that it is used to treat HIV, according to a study published October 5 in the Journal of the National Cancer Institute. Breast cancer is one of the most common causes of cancer deaths in the U.S. with approximately 39,520 women succumbing to the disease in 2011. HER2-postive breast cancer is known to be more aggressive and less responsive to treatments compared to other types of breast cancer. Nelfinavir has been shown to inhibit the growth of some types of cancers and has been used in clinical trials as either a chemotherapeutic agent or a radiosensitizer for cancer therapy. However, its effect on HER2-positive breast cancer is unknown.