Breast cancer is not a single disease. In fact, it has four molecular subtypes, revealed a new study. The study researchers affirmed that every subtype has differnet treatment responses and varying survival rates.

It shall be noted that cases of these subtypes differ as per age, race/ ethnicity and other factors. Researchers from different organizations including the North American Association of Cancer Registries (NAACCR), the American Cancer Society, the Centers for Disease Control and Prevention (CDC) and the National Cancer Institute (NCI) have differentiated breast cancers as per tumor subtypes.

It is expected that it will help in improving treatment of the disease. Betsy A. Kohler, researcher at the NAACCR, said, "Defining breast cancer by the four subtypes will aid breast cancer diagnosis and treatment and help patients better understand how their diagnosis will affect their health".

The researchers have assessed the incidence rate of invasive breast cancer among women aged 85 and using. They assessed data from NAACCR member registries, which had records of breast cancer incidence by four subtypes.

The four subtypes are Luminal A (HR+/HER2-), Luminal B (HR+/HER2+), HER2-enriched (HR-/HER2+) and triple-negative (HR-/HER2-). Among all, the most aggressive breast cancer subtype is HR-/HER2-, and its most commonly found among non-Hispanic black women.

These women also have the highest rates of late-stage breast cancer of all subtypes and the highest rates of undifferentiated pathology. The researchers think that now it could be known as to why non-Hispanic black women have the highest number of breast cancer deaths.

Director of the NCI Dr. Harold Varmus was of the view that the main study finding that breast cancer is not a single disease is a welcome step. The differnet categories will help support activities to prevent and treat breast cancer.