A biomarker reflecting expression levels of two genes in tumor tissue may be able to predict which women treated for estrogen-receptor (ER)-positive breast cancer should receive a second estrogen-blocking medication after completing tamoxifen treatment. In their report being published online in the Journal of the National Cancer Institute, Massachusetts General Hospital (MGH) Cancer Center investigators describe finding that the HOXB13/IL17BR ratio can indicate which women are at risk for cancer recurrence after tamoxifen and which are most likely to benefit from continuing treatment with the aromatase inhibitor letrozole (Femara).
"Most patients with early-stage, ER-positive breast cancer remain cancer-free after five years of tamoxifen treatment, but they remain at risk of recurrence for 15 years or longer after their initial treatment," says Dennis Sgroi, MD, of the MGH Cancer Center and Department of Pathology, lead and corresponding author of the report. "Our biomarker identifies the subgroup of patients who continue to be at risk of recurrence after tamoxifen treatment and who will benefit from extended therapy with letrozole, which should allow many women to avoid unnecessary extended treatment."
Previous research by Sgroi's team, in collaboration with investigators from bioTheranostics Inc., discovered that the ratio between levels of expression of two genes - HOXB13 and IL17BR - in tumor tissue predicted the risk of recurrence of ER-positive, lymph-node-negative breast cancer, whether or not the patient was treated with tamoxifen. The current study of patients from MA.17, the highly successful clinical trial of letrozole, was designed to evaluate the usefulness of the HOXB13/IL17BR ratio for both prognosis - predicting which tamoxifen-treated remained patients at risk of recurrence - and for identifying who could benefit from continued treatment with letrozole.