Living Longer with HER2+ Breast Cancer

Metastatic HER2 breast cancer patients treated with trastuzumab plus hormone therapy surviving longer

(RxWiki News) HER2-positive breast cancers are more aggressive forms of breast cancer. These tumors contain a protein that promotes cancer cell growth. HER2-positive breast cancers can also be driven by the hormone estrogen.

New research suggests a better way to treat HER2-positive.

These research findings suggested that treating HER2-positive metastatic (has spread) breast cancers with both Herceptin (trastuzumab) and hormone-blocking medicines, with or without chemotherapy, may help women live longer.

"Ask your oncologist about combination therapies."

Debu Tripathy, MD, of the University of Southern California (USC) Norris Comprehensive Cancer Center in Los Angeles, CA, led a team of researchers that observed 1,023 newly diagnosed HER2-positive metastatic breast cancer patients.

Data from the RegistHER study were reviewed.   

The researchers found that targeting both the HER2 and the hormone receptors helped women live longer than HER2 therapy alone.

About 25 percent of breast cancers have excessive HER2 proteins. And about half of these cancers also have hormone receptors that make them sensitive to hormones, which help the cancers grow.

Herceptin is the standard of care for treating HER2-positive breast cancer. Various medicines are used to block or interfere with the hormone receptors (HR), including tamoxifen and other medications known as aromatase inhibitors.

The study found that when hormone therapy was combined with Herceptin, women with HR-positive cancers (530) had longer time periods before the disease got worse. This is called progression-free survival (PFS).

Here’s what the researchers discovered:

  • Women who received both hormone and HER2 therapy, along with chemotherapy, had a PFS of 20.4 months compared to 9.5 months for those who had HER2 therapy and chemo alone.
  • Women who had the combined therapy without chemotherapy had a PFS of 13.8 months versus 4.8 months for women who received hormone therapy alone.
  • The median overall survival time for women in the hormone therapy (HT) group only was 35.1 months; while the overall survival of women receiving trastuzumab plus hormone therapy had not yet been reached by the time of publication.
  • The median overall survival for trastuzumab plus chemotherapy plus HT group had not yet been reached by the time of publication, while the overall survival for trastuzumab plus chemotherapy was 36.7 months.

Adam Brufsky, MD, PhD, professor of medicine at the University of Pittsburg, was one of the study authors. He told dailyRx News, “It is gratifying to know that in a registry study like RegistHer, using ‘real world’ patients and outcomes, we see the confirmation of clinical trial data that blockade of HER2, in addition to chemotherapy, results in improved progression-free survival and overall survival in first line metastatic breast cancer."

“This study can aid in significantly improving treatment planning and shared decision-making with patients,” said Dr. Tripathy in a prepared statement.

“It provides a platform for considering hormonal therapy as a standard component of treatment regimens for patients with HER2-positive and hormone receptor-positive metastatic breast cancer.”

This study was published May 7 in The Oncologist.

Genentech, the maker of Herceptin, funded the research. Most of the authors have financial relationships with Genentech. One author also receives research funding from GlaxoSmithKline, Merck, Novartis and Pfizer.

Review Date: 
May 6, 2013