Nearly 70 percent with the most common breast cancer could skip chemo, study says

Women with one of the most common forms of breast cancer may not need to endure chemotherapy, a landmark new study published Monday in the New England Journal of Medicine said.

The researchers hope the findings "greatly expand the number of patients who can forgo chemotherapy without compromising their outcomes. We are de-escalating toxic therapy," Dr. Kathy Albain, chair of oncology research at Loyola University School of Medicine and lead researcher of the study, said.

The majority of women in the study of more than 10,000 -- who had an early stage form of the common type of breast cancer that affects tens of thousands of women -- showed no extra benefit from chemotherapy treatments added to standard treatment alone.

Hormone-receptor-positive, axillary node-negative disease –- the type of breast cancer studied here -- accounts for half of all the breast cancer cases in the U.S., and chemotherapy historically has been part of most women’s treatment regimen after surgery.

After tumor removal, genetic testing is commonly used to predict which type of chemotherapy would give the most benefit. The genetic testing gives cancer a "score" from 0 to 100. The Trial Assigning Individualized Options for Treatment (TAILORx) looked only at HER+, node-negative disease and women with midrange scores on the genetic tests -- a group that has not been researched as much as some others.

The women enrolled in the study were assigned to treatment groups based on their genetic testing score, to examine if chemo plus hormone therapy was beneficial when compared to what has become the standard treatment for this form of breast cancer -- hormone therapy alone.

The majority of women in early stages of this form of breast cancer had basically the same recurrence and survival rates whether they received chemo or not —- overall there were no significant differences, so chemo gave them no advantage.

One difference: In women 50 or younger, chemo was associated with a lower risk of cancer recurrence, although the rates of overall survival were similar. However, most breast cancer occurs in older women.

The study is limited in some ways. First, this is a study of just one form of breast cancer and the authors found that chemo could still benefit some patients with the cancer -- mainly younger women, regardless of their tumor’s genetic "score." Secondly, it looked at early stage cancers that had not yet spread to the lymph nodes.

More than 60,000 women a year in the U.S. could be affected, according to a lead researcher Dr. Joseph A. Sparano of Montefiore Medical Center in New York, and 70 percent of patients who would be potential candidates for chemo could be spared.

Although chemo does help extend life in many cancers, saving patients from the extra treatment could lessen the overall burden of the breast cancer.

"You have to balance risk versus benefit and if you can spare people the negative side effects that chemo brings along with the cost, that's big" ABC News' Chief Medical Editor Dr. Jennifer Ashton said on "Good Morning America."

Eric M. Ascher, DO, is a third-year family medicine resident from New York working in the ABC News Medical Unit.