Studies Question a Breast Cancer Chemo Mainstay

Support for a traditional mainstay of breast cancer chemotherapy treatment may erode after two new studies find that the drug may only benefit a subset of women with the disease.

Many women with breast cancer may be able to safety opt for less intense chemo -- or none at all -- new studies suggest.

(ABCNEWS)

Anthracyclines -- a commonly used class of chemotherapy drugs that also have antibiotic properties -- can cause unpleasant side effects such as nausea, vomiting and, in some cases, serious heart problems.

Being able to reliably tell which breast cancer patients would not likely benefit from the drugs would help doctors spare many women these toxic side effects.

Results from two studies presented Thursday at the 30th annual San Antonio Breast Cancer Symposium now reveal that only women with HER2 positive breast cancer -- a subset which accounts for only about 8 percent of women with breast cancer worldwide -- will benefit significantly from standard anthracycline-based chemotherapy.

Moreover, the research suggests that a different, investigative approach to chemo, which combines Taxotere (doxetaxel)-based therapy with cyclophosphamide, may offer better chances of survival -- along with less severe side effects.

Anthracycline-based therapies spurred controversy within the medical community when they were first introduced nearly 30 years ago. But the contention over the benefit-to-risk ratio of anthracyclines was put to rest when the Oxford Review published evidence supporting this treatment in 1993, citing that use of the anthracycline treatment regimen improved chances of overall survival by 4 to 5 percent.

But Dr. Dennis Slamon, lead investigator of the study presented at SABCS Thursday and chief of the division of hematology/oncology at UCLA's Jonsson Comprehensive Cancer Center, said that his study found that there was actually no benefit whatsoever from the anthracycline treatment in breast cancer patients who did not have HER2 positive breast cancer.

"It's a subgroup of a subgroup [of breast cancer patients] who have this [HER2 positive] alteration that gives us huge benefit of anthracycline, giving us the illusion that in all of breast cancer there's this 4 to 5 percent benefit," he said. "In fact, there's a 30 percent [improvement in overall survival] in this small subgroup that was dragging the whole group up. … And that was dictating treatment decisions for the last almost three decades."