A new test can predict the most effective therapy for all women with breast cancer, including those with hormone-receptor-negative—estrogen-negative, progesterone-negative, Her2- negative, or a combination of all three, according to research conducted at Washington University School of Medicine in St. Louis and reported in advance of publication in the Journal of Clinical Oncology. Using a set of 50 genes, the test goes beyond the existing Oncotype DX test to offer diagnostic help that covers the four known types of breast cancer— luminal A, luminal B, HER2-enriched and basal-like. The last three types are generally considered types with a poor prognosis.
“Unlike a widely used genomic test [Oncotype DX] that applies only to lymph-node negative, estrogen-receptor positive breast cancer, this new genomic test is broadly applicable for all women diagnosed with breast cancer,” says breast cancer specialist Matthew Ellis, M.D., Ph.D., a member of the Siteman Cancer Center at Barnes-Jewish Hospital and Washington University.
Luminal A , a cancer that typically comes with a good prognosis, was not sensitive to chemotherapy, meaning that patients with that type can avoid chemotherapy in favor of hormone-based therapy. Among the poor-prognosis tumor types, basal-like breast cancer was the most sensitive to the chemotherapy and luminal B the least sensitive.
“Luminal B tumors are a very poor prognosis group, and none of the current conventional therapies are particularly effective against it,” Ellis says. “The ability to identify luminal B tumors accurately makes it possible to develop better therapies for this type.”
The researchers are investigating how each tumor type responds to the more than 50 drugs used for breast cancer. Because the gene set can be used with preserved tumor samples, the researchers plan to study tumor samples from breast cancer cases going back a decade or more. Patients in these cases have already been treated, which means the researchers can assess how well therapies worked for various breast cancer types.