Women in the United States with triple–negative breast cancer treated with neoadjuvant therapy are much more likely to choose mastectomies over breast–conserving lumpectomy treatments than are women in Europe and Asia, according to researchers at Dana–Farber Cancer Institute. The findings were released online ahead of the American Society of Clinical Oncology (ASCO) annual meeting.

The study analyzed the surgical choices made by 604 women in the BrighTNess trial, an international randomized phase III clinical trial, in which women with early–stage cancer were given one of three chemotherapy/targeted treatments before surgery. These “neoadjuvant” treatments are designed to shrink tumors before surgery and, in some cases, give women who are initially eligible only for mastectomy the option to be able to undergo lumpectomy instead.

“Given the choice between the two procedures among all patients in the study, 53% of women in the United States underwent mastectomy, compared to 23% of women in developed countries in Europe and Asia,” said Mehra Golshan, MD, FACS, Distinguished Chair of Surgical Oncology at the Dana–Farber Cancer Institute/Brigham and Women's Hospital Cancer Center.

Even more strikingly, “American women who underwent a mastectomy were four times as likely to decide to also remove their unaffected opposite breasts as women in the exact same situation in Berlin or Seoul,” said Golshan, who will be presenting the analysis at a session at the ASCO conference. “Among those who chose mastectomies, and did not have BRCA gene mutations (that increase breast cancer risk), 61% of U.S. women decided to have their opposite breasts removed, compared to 14% of women in Europe and Asia.

“In these decisions, women and their treatment teams in the United States are choosing differently than women and their teams in Europe or Asia,” added Golshan.

Golshan noted that insurance may play a role in these choices, since U.S. insurance organizations typically pay for procedures, including removal of healthy breasts, that may not be supported as fully overseas.

“The BrighTNess clinical study was the first phase III neoadjuvant trial to provide breast cancer patients and surgeons with genetic testing results before the start of treatment,” said Golshan. “However, the trial didn’t ask patients for the reasoning behind their decisions, or surgeons about the information and recommendations they provided. Further research is necessary to determine this complex and layered decision–making process in breast cancer surgery.”