From an interview with
Viji Motilal Nehru, MD
McLeod Oncology and Hematology Associates

Discovering new ways to treat and prevent cancer is the goal of medical research. One cancer that has benefited greatly from research is breast cancer.

In the 1970s, researchers identified an anti-estrogen drug called Tamoxifen as beneficial in the fight against breast cancer. Originally developed for birth control in 1962, it was approved by the Food and Drug Administration (FDA) in 1978 for use in breast cancer treatment after research determined the drug actually blocked the effects of estrogen in the body and in breast cancer cells.

Over the next two decades, Tamoxifen was used in women who had breast cancer as a prevention for relapse, but researchers wondered if women who had a high risk of developing breast cancer would also be protected by the drug. In 1998, a larger breast cancer prevention study revealed that Tamoxifen also decreased the risk of developing breast cancer in high-risk women by 50 percent. High-risk women include those who had a mother or sister with breast cancer.

A follow-up research study comparing Tamoxifen and a drug called Raloxifene or Evista, in 2006, was found to be favorable as well. This study determined that Raloxifene reduced breast cancer risk in post-menopausal women who are high-risk and the drug had a lower chance of serious side effects when compared to Tamoxifen.

Additional research in 2013 looked at the use of Tamoxifen in women who had large tumors or positive lymph nodes at diagnosis and had already completed five years of taking the drug. These results indicated that an additional five years of Tamoxifen gave women a prolonged decrease in breast cancer risk. Now quite often physicians leave women on 10 years of Tamoxifen.

Since these studies, there have been a number of other clinical trials, and today there are four drugs available to high-risk women, depending on whether they are pre-menopausal or post-menopausal including Arimidex and Aromasin, which have both been proven to be useful.

As researchers have continued to study breast cancer, there have also been multiple advancements in care. As a result, there are more chemotherapy agents and targeted treatments to help women, such as immunotherapy, which involves using the patient’s immune system to attack the cancer cells.

For example, women diagnosed with HER2 positive breast cancer are now treated with Herceptin, a form of targeted therapy. Effecting 25 percent of patients, this type of cancer used to be very aggressive with poor outcomes. Since Herceptin-based treatments began in 1998, the outcomes for these patients have improved greatly. In fact, some women who were on the first experimental treatments with Herceptin in 1992 are still in remission.

In December of 2017, the FDA approved the use of another targeted therapy, Perjeta, in combination with Herceptin and chemotherapy after surgery to treat women with early-stage HER2 positive breast cancer, which is has a high risk of recurrence. Both Perjeta and Herceptin work against HER2 positive breast cancers by blocking the cancer cells’ ability to receive growth signals. Working together, these drugs are improving survival in women with high-risk, early-stage HER2 positive breast cancer, as well as those diagnosed with HER2 positive metastatic breast cancer.

In the treatment of triple negative breast cancer, recent clinical trials have led to the approval of three new drugs. For patients with metastatic disease whose tumors express the PD-L1 protein, the addition of immunotherapy drug Tecentriq, an anti-PD-LI antibody, used in combination with chemotherapy drug Abraxane improved progression-free survival. This was also the first FDA-approved regimen for breast cancer to include immunotherapy.

Two other targeted therapies, Lynparza and Talzenna, are PARP inhibitors that are effective for patients with triple negative breast cancer who have inherited BCRA1/2 mutation. These oral medications have been shown to be more effective and better tolerated as compared to traditional chemotherapy. 

Another new class of medicines, Ibrance, Kisqali and Verzenio are now the standard of care in patients with certain types of metastatic breast cancer when combined with hormone therapies. These targeted therapies were the first CDK4/6 inhibitors approved by the FDA. The addition of CDK4/6 has been shown to increase progression-free survival compared to hormone therapy alone.

Thanks to medical research into breast cancer, the discovery of new drugs continues to change the lives of patients tremendously and improve survival. 

To learn more, speak with an oncologist near you.