A New Standard Treatment for Stage I, HER2-Positive Breast Cancer?

Eric Winer, MD

Results of a phase II study showed that women with small, stage I HER2-positive tumors who received a combination of lower-intensity chemotherapy and the targeted drug trastuzumab following surgery were highly unlikely to have the cancer recur within 3 years.

The study found that 98.7% of the participants treated with the combination after surgery were alive and free of invasive breast cancer 3 years after receiving the treatment.

Many previous studies have excluded women with HER2-positive breast tumors less than 2 cm in diameter that hadn’t spread to nearby lymph nodes from clinical trials of trastuzumab, because it wasn’t considered prudent to expose them to an investigational drug, given the relatively low risk that the disease would recur.

Without a single, standard treatment for this group of patients, treatment approaches have varied widely.

These phase II results, published in the New England Journal of Medicine, may help establish the therapy as the first standard treatment approach for this group of patients, the authors state.

“Women with small, HER2-positive, node-negative [no sign of spread to adjacent lymph nodes] breast tumors have a low, but still significant, risk of recurrence of their disease,” Eric Winer, MD, director of the Breast Oncology Program at the Susan F. Smith Center for Women’s Cancers at Dana-Farber, said in a statement. “This study demonstrates that a combination of lower-intensity chemotherapy and trastuzumab—which is associated with fewer side effects than traditional chemotherapy regimens—is an appealing standard of care for this group of patients.”

For this study, researchers enrolled 406 patients with HER2-positive, node-negative breast tumors smaller than 3 cm. The participants were treated with paclitaxel and trastuzumab for 12 weeks, followed by 9 months of trastuzumab alone.

In addition to the high likelihood of preventing cancer recurrence, the study also found that the side effects were generally milder than those associated with traditional chemotherapy regimens.

“We’re committed to identifying treatment regimens that are geared not only to the specific biological features of a woman’s cancer, but also to the stage of the cancer, the size of the tumor, and how far it has advanced,” lead author, Sara Tolaney, MD, MPH, of the Susan F. Smith Center for Women’s Cancers at Dana-Farber, said in a statement. “This study is a prime example of the value of that approach.”