FRIDAY, Dec. 15 (HealthDay News) -- U.S. researchers have developed two genomic tests to help doctors better predict how breast cancer patients will respond to hormonal therapy or chemotherapy.

Details about the new tests were to be presented Thursday and Friday at the San Antonio Breast Cancer Symposium.

"We are moving these tests towards clinical trials, where we can measure improvements in treatment response and track how physicians and patients use this information to make better decisions about treatment," one of the team leaders, Dr. Lajos Pusztai, an associate professor in the department of breast medical oncology at the University of Texas M.D. Anderson Cancer Center, said in a prepared statement.

The multi-gene predictor of response to chemotherapy was developed by analyzing 780 different gene combinations and narrowing the test down to a small set of genes. When it was used in 51 breast cancer patients who received chemotherapy, the test accurately predicted 12 of 13 who achieved a complete response and 27 of 28 patients with residual cancer.

The other test is a genomic index that predicts 10-year survival for patients who receive post-operative hormonal therapy with the drug tamoxifen. The Sensitivity to Endocrine Therapy (SET) index was tested in 267 breast cancer patients who received tamoxifen without chemotherapy for five years after surgery.

"There was a strong relationship between their SET index score and the probability of there being no disease 10 years later," Dr. W. Fraser Symmans, an associate professor in the department of pathology, said in a prepared statement.

A score in the top 35 percent of the index was significantly associated with relapse-free survival at 10 years. Women with scores in the lower 50 percent of the index derived little benefit from tamoxifen treatment alone. A separate analysis showed they were more likely to benefit from chemotherapy, the researchers said.