Majority of women with breast cancer do not need chemotherapy

August 22, 2015

In a report delivered at the annual meeting of the American Society for Therapeutic Radiation and Oncology in Denver, principal researcher Dr. Gary Freedman, of Fox Chase Cancer Center in Philadelphia, presented the results of a study which involved 471 women diagnosed with breast cancer.

All had undergone lumpectomies and received radiation and 5 years of Tamoxifen, and in the group 152 women also received chemotherapy with aromatase inhibitors.

The study group were analyzed to determine which women benefited from the addition of chemotherapy.

Freedman and colleagues found that women who were disease-free 5 years after surgery, radiation and Tamoxifen had just a 2.5 percent risk of their cancer returning at 10-year follow-up.

According to Freedman in clinical practice, a benefit level of greater than 3 percent is commonly used to select patients for chemotherapy, and assuming a 40 percent reduction in the risk of the cancer returning, by adding an aromatase inhibitor to 5 years of Tamoxifen therapy, the absolute benefit would occur in 1 percent of patients.

Freedman does say however that some women may benefit from chemotherapy, for example those who are premenopausal, have cancer in several lymph nodes, or have major diseases in addition to their cancer.

He says that for women who are over 60, the overwhelming number of deaths are due to non-breast cancer causes, which further minimizes the benefits of chemotherapy.

The NCCTG trial N9831, of which Dr. Perez was the primary investigator, was a cooperative effort with the Eastern Cooperative Oncology Group (ECOG), the Southwest Oncology Group (SWOG), and the Cancer and Leukemia Group B (CALGB). It compared three chemotherapy regimens, two that included trastuzumab therapy -- one dosage concurrent with weekly paclitaxel, the other after completion of paclitaxel. The NSABP trial B-31 compared one chemotherapy regimen against the same regimen with weekly trastuzumab and tri-weekly (or weekly) paclitaxel. Investigators determined that the treatments being compared were similar, and results from the two studies were combined to form a joint analysis, excluding the NCCTG N9831 trial group that looked at trastuzumab administered sequentially after paclitaxel.

In addition to Dr. Perez, members of the NCCTG and Mayo Clinic research team included Vera Suman, Ph.D.; Thomas Pisansky, M.D.; Leila Kutteh, M.D.; Daniel Visscher, M.D.; Robert Jenkins, M.D., Ph.D.; Shaker Dakhil, M.D.; Wilma Lingle, Ph.D.; and James Ingle, M.D. Other collaborating researchers on N9831 included Nancy Davidson, M.D. (ECOG); Silvana Martino, D.O. (SWOG); and Peter Kaufman, M.D. (CALGB).

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