Mastectomy more common among US women with triple-negative breast cancer

CHICAGO — Women in the United States who underwent neoadjuvant therapy for triple-negative breast cancer appeared more likely than those in Europe and Asia to choose mastectomy instead of breast-conserving surgery, according to study results presented at the ASCO Annual Meeting.

“Given the choice between the two procedures among all patients in the study, 53% of women in the United States underwent mastectomy compared with 23% of women in developed countries in Europe and Asia,” Mehra Golshan, MD, FACS, distinguished chair of surgical oncology at Dana-Farber Cancer Institute and Brigham and Women’s Hospital Cancer Center, said in a press release.

Golshan and colleagues analyzed data from 604 women enrolled in the international, phase 3 BrighTNess trial, which compared three neoadjuvant treatment regimens — veliparib (ABT-888, AbbVie), carboplatin and paclitaxel; placebo with carboplatin and paclitaxel; or placebo with paclitaxel followed by doxorubicin and cyclophosphamide — for early-stage breast cancer.

Surgeons used clinico-radiographic criteria before and after neoadjuvant systemic therapy to determine patient candidacy for breast-conserving surgery.

Sixty-eight percent of patients eligible for breast-conserving surgery after neoadjuvant treatment underwent the procedure. Pathologic complete response rates did not differ between breast-conserving surgery–eligible patients who underwent that procedure versus mastectomy (55% vs. 53%).

Of 141 patients deemed ineligible for breast-conserving surgery at baseline, 75 (53%) became eligible after neoadjuvant treatment; of this group, only 42 (56%) opted to undergo that surgery. Rates of pathologic complete response were 49% among patients who became eligible after treatment and 36% among those who remained ineligible.

Patients with germline BRCA mutations (n = 84) appeared less likely to undergo breast-conserving surgery, even if clinicians deemed them eligible for the procedure (rate among all patients, 26%; eligible patients, 32%).

Women in North America appeared less likely to choose breast-conserving surgery than European and Asian women (55% vs. 80%; P < .0001), even among those without BRCA mutations who were eligible for the surgery (61% vs. 85%; P < .0001).

“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,” Golshan said. “Among those who chose mastectomies and did not have BRCA mutations, 61% of U.S. women decided to have their unaffected breasts removed, compared with 14% of women in Europe and Asia.”

Insurance may affect these choices. Many U.S. insurance companies pay for removal of unaffected breasts, but that may not be the case overseas, Golshan said.

This represents the first phase 3 neoadjuvant trial to provide patients with breast cancer and their surgeons genetic results before the start of treatment.

“However, the trial did not ask patients for the reasoning behind their decisions, or surgeons about the information and recommendations they provided,” Golshan said. “Further research is necessary to determine this complex and layered decision-making process in breast cancer surgery.” – by Alexandra Todak

Reference:

Golshan M, et al. Abstract 514. Presented at: ASCO Annual Meeting; June 2-6, 2017; Chicago.

Disclosure: Golshan reports a consultant/advisory role with AbbVie. Please see the abstract for a list of all other researchers’ relevant financial disclosures.