No approved targeted therapies exist to treat triple-negative breast cancer, but new chemotherapeutic treatment strategies are helping shrink tumors so that less breast tissue needs to be removed during surgery. New research led by Brigham and Women's Hospital (BWH) finds that breast conserving therapy - or the removal of less breast tissue via a lumpectomy - was successful in more than 90 percent of the women who became eligible for this procedure after treatment with chemotherapy. Despite these findings, 31 percent who were eligible for breast conserving therapy chose to have the entire breast removed via mastectomy.
The complete manuscript of this study and its presentation at the American Surgical Association's 135th Annual Meeting, April 23, 2015, in San Diego, California, is anticipated to be published in the Annals of Surgery pending editorial review.
"In general, if possible, we try to offer breast conserving therapy as a preferred option for women with early stage breast cancer," said corresponding author Mehra Golshan, MD, Director of Breast Surgical Services at Dana-Farber/Brigham and Women's Cancer Center. "One of the reasons we use chemo first is to potentially allow women who originally needed to have the entire breast removed because of more advanced disease to now be eligible for breast conserving therapy. We see though that a significant number of patients who were eligible still ended up deciding to have their breast removed."
The new work does not explain why patients and their surgeons made this choice. Previous studies have found that for those who are eligible for breast conserving surgeries such as a lumpectomy, the rate of survival for patients who chose to have a lumpectomy is the same as for those who chose to have a mastectomy. A study by von Minckwitz et al. found that in a population from Germany, nearly 75 percent of patients underwent breast conserving therapy for similar type tumors, much higher than the overall breast conserving therapy rate of 47 percent reported in the current study.
"We don't have an answer for why this is the case, but we hope that this work encourages more patients and clinicians to think about why this is happening and what we can do to address this," said Golshan, who is also director of Breast Surgical Services at the Susan F. Smith Center for Women's Cancers at Dana-Farber Cancer Institute. "It's a work in progress."
The new study examined the impact of adding carboplatin - a platinum-based chemotherapeutic agent - and/or bevacizumab - a drug designed to slow the growth of new blood vessels - to the standard regimen of chemotherapy given to patients with triple-negative breast cancer. The team found a trend suggesting that the addition of one or both drugs increased the number of patients eligible for breast conserving therapy.
"In triple-negative breast cancer patients, we continue to increase the complete pathologic response rate with our new drug combinations," said senior author David Ollila, MD, James and Jesse Distinguished Professor of Surgery at University of North Carolina School of Medicine, co-director of the UNC Breast Program and a member of the UNC Lineberger Comprehensive Cancer Center. "On our trial, more patients were eligible for breast preservation. Despite these advances, more patients chose mastectomy as their surgical procedure. The reasons for this paradox need to be further explored."
"A lot of things go into making this decision, but we must take into consideration the high likelihood of success in patients deemed candidates for breast conserving therapies," said Golshan.
Golshan and his colleagues note that they did not study specific patient or surgeon factors such as fear of cancer recurrence or whether a patient harbored mutations in genes such as BRCA. Future studies could shed light on how these variables impact the choice between mastectomy and breast conserving therapy.
Research reported in this publication was supported by the National Cancer Institute of the National Institutes of Health under Award Numbers U10CA180821 and U10CA180882 (to the Alliance for Clinical Trials in Oncology), CA180888 (SWOG), U10CA180791, and U10CA180867. This work was also supported in part by grants from the Breast Cancer Research Foundation and Genentech.