by Aimee Keenan-Greene

Scientists say they now have a new genetic test to predict which breast cancer patients will benefit from chemotherapy, according to a study in the May 11 issue of the Journal of the American Medical Association.
This means doctors could know which patients will respond better, and what treatments should be avoided. A prospective multicenter study was conducted by Christos Hatzis, PhD, of Nuvera Biosciences Inc, Woburn, Massachusettsfrom June 2000 to March 2010 at the M. D. Anderson Cancer Center to develop and test genomic predictors for neoadjuvant chemotherapy.  Patients were newly diagnosed ERBB2 (HER2 or HER2/neu), negative breast cancer treated with chemotherapy containing sequential taxane and anthracycline-based regimens (then endocrine therapy if estrogen receptor [ER]–positive).  Different predictive signatures for resistance and response to preoperative (neoadjuvant) chemotherapy (stratified according to ER status) were developed from gene expression microarrays of newly diagnosed breast cancer (310 patients).  Breast cancer treatment sensitivity was then predicted using the combination of signatures for: sensitivity to endocrine therapy, chemoresistance, and  chemosensitivity, with independent validation (198 patients) and comparison with other reported genomic predictors of chemotherapy response. Patients in the independent validation cohort (99% clinical stage II-III) who were predicted to be treatment sensitive (28%) had 56% (95% CI, 31%-78%) probability of excellent pathologic response and DRFS of 92% (95% CI, 85%-100%), with an ARR of 18% (95% CI, 6%-28%). This means 92 percent of the women the test predicted would respond to chemotherapy survived three years without relapsing, giving them an 18 percent lower risk of dying compared to those predicted as 'non-responders' to treatment.Survival was predicted in ER-positive (30% predicted sensitive; DRFS, 97% [95% CI, 91%-100%]; ARR, 11% [95% CI, 0.1%-21%]) and ER-negative (26% predicted sensitive; DRFS, 83% [95% CI, 68%-100%]; ARR, 26% [95% CI, 4%-48%]) subsets and was significant in multivariate analysis. Other genomic predictors showed paradoxically worse survival for patients predicted to be responsive to chemotherapy.  Distant relapse–free survival (DRFS) if predicted treatment sensitive and absolute risk reduction ([ARR], difference in DRFS between 2 predicted groups) at median follow-up (3 years). Researchers say a genomic predictorcombining ER status, predicted chemoresistance, predicted chemosensitivity, and predicted endocrine sensitivity identified patients with high probability of survival following taxane and anthracycline chemotherapy. 

Last year, more than 207,000 women in the U.S. were diagnosed with breast cancer, and almost 40,000 died from the disease, according to the National Cancer Institute.