ASCO Updates Guidelines for HER2-Negative Breast Cancer

Approximately 80% of all breast cancers diagnosed in the United States are HER2-negative.

The American Society of Clinical Oncology (ASCO) has updated its clinical practice guideline on both targeted therapies and chemotherapy treatment for women with HER2-negative breast cancer, which makes up approximately 80% of all breast cancers diagnosed in the United States.

According to the guideline, hormonal therapy, rather than chemotherapy, is the preferred first-line therapy for patients with estrogen receptor–positive metastatic breast cancer, except in cases of immediate life-threatening disease or when a patient is suspected to be resistant to hormonal treatment. Subsequent therapy should consist of sequential chemotherapy. There is no single agent that is preferred as a first-line or later-line therapy. Rather, the decision should be based on patient factors, including prior therapies, toxicity, performance status, comorbidities, and the patient’s preference. It was also stressed that the role of bevacizumab for breast cancer is still controversial.

Based on the most up-to-date evidence-based studies, the guideline provides a tool for clinicians to choose the best therapy for each patient. The ASCO expert panel analyzed studies from 1993 to May 2013, including 30 first-line and 29 second-line and subsequent clinical trials, as well as 20 meta-analyses and systematic reviews.

“There are many different types of treatments available but some are unnecessarily toxic,” said Ian E. Smith, MD, co-chair of the expert panel, in a statement. “This guideline emphasizes that breast cancer can often be controlled with less intensive approaches that offer a better quality of life for patients. Patients should be involved in decisions about their own treatment and also encouraged to participate in clinical trials whenever possible.”

Summary of the Guideline Recommendations

1. Standard first-line therapy should be hormonal therapy for women with hormone receptor–positive metastatic breast cancer, except in cases of immediate life-threatening disease or in the presence of possible resistance to hormonal therapy.

2. Chemotherapy agents should be given sequentially, not in combination, to reduce adverse events and so as not to diminish quality of life.

3. Clinicians and patients should make treatment decisions together, considering prior therapies, potential side effects, treatment schedule, existing chronic diseases, and patient preference.

4. Bevacizumab should only be considered with single-agent chemotherapy in the presence of immediate life-threatening disease or severe symptoms. While bevacizumab can shrink tumors and delay disease progression in some patients, according to the guideline, the antibody has not been shown to extend overall survival and is not currently approved by the US Food and Drug Administration for the treatment of breast cancer.

5. No other targeted agents should be used in addition to, or as a replacement for, chemotherapy. Only everolimus, a targeted agent against the mTOR pathway, is approved in conjunction with exemestane, a hormonal therapy, for women with early-stage hormone receptor–positive breast cancer, when the disease is still responsive to hormonal therapy.

6. Palliative care should be initiated early and offered throughout the care of breast cancer patients.

7. Since there is no cure for advanced breast cancer, clinicians should encourage all eligible HER2-negative breast cancer patients to participate in clinical trials to potentially benefit from promising experimental treatments.