A 21-year study by Kaiser Permanente found that the most common and least aggressive subtype of breast cancer still poses a risk of death more than 10 years after women are diagnosed with the disease.

The study, published in Cancer Epidemiology, Biomarkers & Prevention, analyzed nearly 1,000 women from Kaiser Permanente Southern California.1 Researchers determined that women with HER2-enriched and luminal A tumors–a subtype of breast cancer that is thought to have the best prognosis– were still at risk of dying more than 10 years after diagnosis. They also found that women with HER2-enriched and luminal B tumors had an approximate 2-fold greater risk of death from breast cancer than women diagnosed with luminal A tumors, which is consistent with previous studies.

Lead author Reina Haque, PhD, MPH, from Kaiser Permanente Southern California's Department of Research and Evaluation in Pasadena, California, says the study demonstrates that women with luminal A tumors might benefit from extended treatment to improve their chances of long-term survival.

The 4 breast cancer subtypes include the luminal A and luminal B subtypes, the basal-like subtype, and the HER2- enriched subtype. The luminal A subtype constitutes 42% to 59% of all breast cancer patients. Dr. Haque and colleagues say future studies should focus on identifying factors that are associated with longer survival in women with luminal A tumors. Further, they recommend that other studies should examine how the association between breast cancer molecular subtypes and survival rates vary among different racial and ethnic groups.


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