Women with triple-negative breast cancer and no more than three positive lymph nodes following a mastectomy have a higher risk of recurrence than similar women whose disease is not classified as triple-negative.

Triple-negative disease occurs in 10% to 25% of all breast cancer cases. Some of the most successful breast cancer therapies target certain receptors that have the ability to cause the cancer to spread. These targeted receptors including estrogen receptors, progesterone receptors, or HER2/neu protein, and they are absent from triple-negative breast cancer cells. Thus, triple-negative breast cancer is resistant to some of these common treatments.

The research team focused on if women with triple-negative breast cancer would benefit from post-mastectomy radiation therapy. They retrospectively identified 22 women with no more than three positive lymph nodes whose initial mastectomy tissue was available for study. None of these patients received radiation after their mastectomy. The specimens from these patients were compared to specimens from 28 women with no more than three positive lymph nodes but no evidence of disease at their last follow-up visit. The controls were matched for age, within 3 years, and follow-up duration, which was less than 5 years versus more. The tissue specimens were examined for signs of disease.

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Women whose breast cancer was classified as triple-negative had an associated higher risk of local recurrence. Conversely, women whose breast cancer was estrogen-receptor positive, progesterone-receptor positive, or a combination of both had a strong association with a lower risk of local recurrence. A lower risk was also associated with the use of chemotherapy.

“By further defining the risk of local recurrence in women with triple negative breast cancer, clinicians can better determine whether radiation treatment should be part of postmastectomy therapy,” noted the lead author of the research, Atif J. Khan, MD, a radiation oncologist at The Cancer Institute of New Jersey and an assistant professor of radiation oncology at Robert Wood Johnson Medical School.

This work was presented at the 54th Annual Scientific Meeting of the American Society for Radiation Oncology (ASTRO) in Boston.