LUMPECTOMY BETTER THAN MASTECTOMY FOR TRIPLE NEGATIVE PATIENTS?

NEW YORK (Reuters Health) Jun 16 - Breast-conserving therapy may provide better five-year locoregional control for women with triple-negative breast cancer than modified radical mastectomy without adjuvant radiation, according to a retrospective study from Canada.
National Comprehensive Cancer Network guidelines recommend adjuvant radiotherapy after modified radical mastectomy based only on tumor size and lymph node status, without regard to biologic subtype.
But the new results challenge the "paradigm in breast cancer that breast-conserving surgery followed by radiation therapy is equivalent to mastectomy alone" in all patients, said Dr. Jean-Philippe Pignol of Sunnybrook Health Sciences Centre in Toronto and colleagues in an editorial.
Instead, mastectomy for aggressive disease like triple-negative breast cancer may be the wrong approach, they wrote.
As reported online June 13 in the Journal of Clinical Oncology, Dr. Bassam Abdulkarim and colleagues at McGill University in Montreal reviewed all cases of triple-negative breast cancer at their institution from 1998-2008 (n=768), i.e., all women whose tumors didn't express receptors for estrogen, progesterone, or human epidermal growth factor receptor-2 (HER2).
As initial treatment, 42% of patients received breast-conserving therapy, 37% had modified radical mastectomy alone, and 21% had modified radical mastectomy plus adjuvant radiotherapy. Eighty-five percent received chemotherapy. The median follow-up in the study was 7.2 years.
Five-year, locoregional recurrence-free survival was 94%, 85%, and 87% for breast-conserving therapy, modified radical mastectomy and modified radical mastectomy plus radiotherapy, respectively (P<.001).
When investigators analyzed only the type of initial treatment, the rate of locoregional recurrence was significantly higher in the modified radical mastectomy group (HR, 2.61, P<.001) and the modified radical mastectomy plus radiotherapy group (HR, 2.38, P<.001) compared to patients receiving breast conserving therapy.
When they analyzed multiple variables, including tumor size, grade, lymph node status, lymph vascular invasion and adjuvant chemotherapy, modified radical mastectomy without radiotherapy was an independent predictor of local recurrence (HR 3.44, P<.001) however, there was no difference between those who also underwent radiotherapy and those who received breast conserving therapy.
The investigators also looked separately at 468 women with T1-2N0 disease. In this group, five-year locoregional recurrence-free survival was 96% after breast-conserving therapy and 90% after modified radical mastectomy without radiation (P=.022). On multivariate analysis, modified radical mastectomy without radiotherapy was the only independent factor associated with higher local recurrence (HR, 2.53, P=.027).
"Taken together, our findings emphasize that the current guidelines should take into account the intrinsic risk associated with this biologic subtype," the investigators, the authors say.
In their editorial, Dr. Pignol and colleagues say that clinically, the data should be used to inform triple-negative breast cancer patients of their likely outcomes. Also, they suggest, "adjuvant radiotherapy after mastectomy should at least be discussed" with such women.