SABCS Surgical Studies With Practice-Changing Potential Form Basis of Review of Noteworthy Data

Beth Fand Incollingo @fandincollingo
Published: Monday, May 05, 2014
J. Michael Dixon, MD, OBE

J. Michael Dixon, MD, OBE

The value of surgery in some women with metastatic breast cancer was challenged by data from studies presented at the recent San Antonio Breast Cancer Symposium (SABCS).

In an interview, J. Michael Dixon, MD, OBE, discussed the results of studies on that topic and other notable surgical findings presented at SABCS in December 2013 (Table), including a new approach to detecting sentinel lymph nodes and data on avoiding radiotherapy (RT) in elderly patients.

The professor of Surgery, consultant surgeon, and clinical director of the Breakthrough Research Unit at the University of Edinburgh in Scotland shared highlights of that research with attendees at the 31st Annual Miami Breast Cancer Conference in March. Dixon served as one of the program directors for the conference.

Surgery Questioned in Some Metastatic Breast Cancers

There were two randomized studies and one registration study in patients with stage IV breast cancer presented at SABCS, each looking at the value of surgery, Dixon said.

“Two randomized studies looked at surgical removal of primary tumors with or without involved axillary lymph nodes in women with metastatic breast cancer. Despite the literature indicating that surgery appeared advantageous in women with metastatic disease, neither of these studies showed any advantage for surgery,” Dixon said.

One study conducted in India (Abstract S2-02), he said, compared overall survival (OS) in women with metastatic breast cancer who were treated with anthracycline-based chemotherapy, responded, and then were given either locoregional treatment (LRT) or no LRT.

Locoregional treatment consisted of surgery— either breast-conserving surgery or mastectomy plus axillary lymph node dissection—followed by RT. Both groups received standard endocrine therapy after the last cycle of chemotherapy, if indicated. The median follow-up was 17 months, and 218 deaths had been recorded at data cutoff. The authors, Badwe et al, found that median OS in the LRT and no-LRT arms, respectively, was 18.8 and 20.5 months (HR = 1.07; 95% CI, 0.82- 1.40; P = .60), and the corresponding 2-year OS rates were 40.8% and 43.3%, respectively. After adjusting for age, estrogen receptor (ER) status, HER2 receptor status, site of metastases, and number of metastatic lesions in a Cox regression model, there was no significant difference in OS between the two arms (HR = 1.00; 95% CI, 0.76- 1.33; P = .98), the investigators reported. “Locoregional treatment of the primary tumor and axillary nodes has no impact on OS in patients diagnosed with [metastatic breast cancer] at initial presentation who have responded to frontline chemotherapy,” Badwe et al wrote. “We were unable to identify any subgroups that are likely to benefit from [LRT]. Such treatment should be reserved for women who need it for palliative reasons.”

A second study (Abstract S2-03), this one conducted in Turkey, compared immediate LRT at diagnosis against systemic therapy in a group of women with metastatic breast cancer. The extent of metastases was less than in the Indian study, but the findings were the same—that LRT did not improve survival, except in a specific subgroup.

Finally, a US registration study presented by King et al (Abstract P2-18-09) identified a group of women who were found to have metastases within 3 months of surgery who had a more favorable outlook compared with women who had stage IV disease at first presentation. Among the stage IV patients, though, those who had surgery did not seem to have a better outcome. A commentary by an investigator leading the US randomized study questioned whether this study was sufficiently powered to detect small differences in outcome from surgery, yet still concluded that the pendulum had swung away from the belief that surgery in patients with metastatic breast cancer improves OS.

Study Challenges Axillary Lymph Node Dissection in Clinically N0 Patients

Dixon also pointed to notable 10-year follow-up data from NSABP B-32, a prospective, randomized phase III trial (Abstract S2-05) that compared sentinel node resection with or without conventional axillary dissection in clinically node-negative patients. Findings by Julian et al that were presented at SABCS focused on secondary endpoints of that trial, concerning the potential effects of occult metastatic disease on outcomes.

The top-line finding of the follow-up data, Dixon said, is that axillary lymph node dissection is unnecessary in this population, regardless of the presence (diagnosed or not) of occult metastatic disease.

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