Surgery no help in metastatic breast cancer
Surgery no help in metastatic breast cancer
16/12/2013
Breast cancer found metastatic at diagnosis had similar outcome even if the primary tumor and axillary lymph nodes were removed, two clinical trials showed.
A 350-patient trial in India showed a median overall survival of about 18 months, with or without surgical removal of the primary tumor and axillary nodes. Local therapy was associated with a nonsignificant reduction in locoregional recurrence, but surgically treated patients had a significantly higher incidence of distant metastases.
"Locoregional treatment of the primary tumor in women presenting with metastatic breast cancer did not result in any overall survival benefit and hence should not be offered as a routine practice," Rajendra Badwe, MD, of Tata Memorial Center in Mumbai, India, said here at the San Antonio Breast Cancer Symposium. "Surgical removal of the primary tumor in these women appears to confer a growth advantage on distant metastases."
An ongoing study from Turkey also showed no difference in survival after more than 40 months of follow-up in patients treated with surgery and systemic therapy, or just with systemic therapy. A subgroup analysis found an apparent survival benefit in women with solitary bone metastases, but not in any other groups.
Almost 25 years ago, studies involving laboratory animals suggested that removal of a primary tumor induced release of a growth-stimulating substance that had the potential to influence metastatic behavior.
Multiple clinical studies published since 2000 have shown mixed results following removal of a primary tumor. Some studies demonstrated a survival benefit whereas others did not. However, all of the data came from retrospective and observational studies conducted at a single institution, said Badwe.
To provide data from a prospective study, investigators enrolled and randomized patients with metastatic breast cancer at diagnosis to local therapy or no local therapy. Patients assigned to local therapy, in consultation with their treating physicians, could opt for breast-conserving surgery or mastectomy.
The primary endpoint was overall survival. After follow-up for as long as 72 months, overall survival was 20.5% in patients who did not have surgery and 19.2% in those who did. Subgroup analysis failed to identify any group of patients that benefited from surgical removal of the primary tumor and axillary lymph nodes.
Not unexpectedly, the surgery group had significantly better local progression-free survival (HR 0.16, P=0.00), said Badwe. However, the no-surgery group had an advantage in distant metastasis-free survival, consistent with the animal studies from more than two decades ago (HR 1.42, P=0.01).
Breast cancer specialists in Turkey conducted a similar trial, randomizing almost 300 patients with stage IV disease at diagnosis to local plus systemic therapy or only systemic therapy. The groups did not differ significantly with respect to demographics or any clinical characteristics, including systemic regimens, said Atilla Soran, MD, formerly a resident at the Ankara Numune Teaching & Research Hospital in Turkey and now at the University of Pittsburgh.
Analysis of data after 46 months of follow-up in the surgery group and 42 months in the no-surgery group yielded a hazard ratio of 0.76 in favor of surgery. However, the confidence intervals crossed the point of unity, making the results nonsignificant (95% CI 0.49-1.16, P=0.20).
Subgroup analyses showed no difference by hormone receptor status, age, HER2 status, triple-negative disease, number of involved organs, or bone-only metastases. The analyses did show that patients with a single bone metastasis (N=53) had a significant survival benefit with surgery (HR 0.23, P=0.02).
Consistent with the findings reported by Badwe, the study showed a higher incidence of locoregional progression in patients who received only systemic therapy (3.6% versus 0.7% for the surgery group).
Investigators identified other subgroups that will be watched closely during continued follow-up, said Soran. Patients younger than 55 had a nonsignificant trend toward better survival with surgery. On the other hand, aggressive phenotypes and patients with multiple liver or lung metastases fared worse with surgery.
The findings do have applicability to North American populations, where 5% to 10% of breast cancer patients have metastatic disease at diagnosis, said Kent Osborne, MD, of Baylor College of Medicine in Houston, who moderated a press briefing that included a summary of Badwe's study. The percentage is not far behind the estimated 10% to 15% of patients who have metastatic disease at diagnosis in India.
Source: MedPage Today: http://www.medpagetoday.com/MeetingCoverage/SABCS/43441