Surgical removal of primary breast cancer tumors had no benefit on overall survival in women who presented with metastatic breast cancer, according to the results of a study presented at SABCS.
SAN ANTONIO-Surgical removal of primary breast cancer tumors had no benefit on overall survival in women who presented with metastatic breast cancer, according to the results of a study presented at the 2013 San Antonio Breast Cancer Conference.
Instead, removal of the primary tumor conferred an improved local progression-free survival at the cost of a worsened distant progression-free survival.
“The locoregional treatment of the primary tumor in women presenting with metastatic breast cancer did not result in any overall survival benefit and hence forth should not be offered as a routine practice,” said Rajendra Badwe, MD, director of the Tata Memorial hospital, Mumbai, India, who presented the results of a randomized controlled trial examining the effects of removing the primary tumor and axillary lymph nodes on overall and progression-free survival.
Unfortunately, much of the oncology world is divided on this issue, Badwe said. Among the evidence against mastectomy are experiments conducted in the 1980s by Bernard Fisher. Fisher published the results of an animal experiment in which he found that the removal of a primary tumor conferred a growth advantage to the secondary tumor. In the last decade, however, there have been many studies, all of them retrospective, which have looked at the survival of patients who have had surgery. A systematic review of these studies showed a 35% reduction in deaths in patients who have had surgical intervention.
To further assess this issue, Badwe and colleagues conducted a prospective trial of 350 women presenting with metastatic breast cancer between 2005 and 2013. All patients had an objective response to 6 cycles of chemotherapy and were randomly assigned to either locoregional therapy (n = 173) or no locoregional therapy (n = 177). Patients were stratified by endocrine receptor status, site of metastases, and number of metastases. Women in the locoregional therapy arm underwent surgery and radiation therapy. When indicated, women received endocrine therapy after surgery.
Overall survival analysis showed no statistically significant difference in outcomes between the two treatment arms (HR = 1.04; 95% CI, 0.80-1.34; P = .79). When looking at the secondary endpoints, subgroup analyses showed no difference in overall survival by menopausal status, metastasis site, number of metastases, or hormone sensitivity.
However, there was a more than 80% local progression-free survival rate in those women who underwent surgery compared with those who did not (HR = 0.16; 95% CI, 0.10-0.26; P < .001).
“With such a huge difference in locoregional control, why did it not translate into an overall survival benefit?” Badwe asked.
The results indicated that women who underwent surgery and had improved locoregional control and significantly worse distant progression-free survival compared with women who did not undergo surgery (HR = 1.41; 95% CI, 1.08-1.85; P = .01).
“I’m sure a lot of oncologists who believe in conventional wisdom and don’t provide locoregional treatment will feel a lot more comfortable looking at these results,” said Badwe. “As for those who have changed practice based on the retrospective study history, they would have to rethink.”