New focus on tumor subtypes could help patients, according to medical groups
WebMD News from HealthDay
By Robert Preidt
MONDAY, March 30, 2015 (HealthDay News) -- Breast cancer isn't the same for every woman, even at the cellular level, according to a new statement from four major medical groups focused on the disease.
The report was issued Monday by the American Cancer Society, the U.S. Centers for Disease Control and Prevention, the U.S. National Cancer Institute, and the North American Association of Central Cancer Registries. They say that classifying breast cancers according to tumor subtypes could help improve treatment of the disease.
The report "assesses breast cancer as four molecularly defined subtypes, not as a single disease," National Cancer Institute director Dr. Harold Varmus said in an institute news release. "This is a welcome step, [resulting from] medically important information that already guides therapeutic strategies for these subtypes," he said.
The four major molecular subtypes are categorized according to their hormone receptor (HR) status, meaning a chemical receptor lying on breast cancer cells that reacts to hormones such as estrogen. Categorization is also dependent on a tumor cell's activity around the HER2 gene. Both factors can affect how a tumor acts and might be treated, experts say.
The four tumor types are: Luminal A (HR+/HER2-), Luminal B (HR+/HER2+), HER2-enriched (HR-/HER2+), and triple negative (HR-/HER2-).
Experts have long known that the four subtypes respond differently to treatment and have different survival rates, according to the report published March 30 in the Journal of the National Cancer Institute.
Cancer registries across the United States are now recording these breast cancer subtypes, the groups noted, and this new data will help researchers more accurately rank breast cancer by risk. It should also help patients better understand each subtype's impact on their health, the authors said.
Some differences in breast cancer rates and deaths between racial and ethnic groups are also tied to differences in the rates of different breast cancer subtypes emerging in those groups, the report suggests.
It said there were unique racial/ethnic group patterns by age, poverty level, geography and specific tumor characteristics. For example, rates of HR+/HER2- breast cancer -- the least aggressive subtype -- were highest among white women.
source : Breast Cancer Is Not One Disease, Experts Say