Women with early-stage invasive breast cancer who undergo breast-conserving therapy (BCT) have a higher rate of disease-specific survival than those who undergo mastectomy, according to an analysis published online January 15 in JAMA Surgery. This is the second large observational study in the past year to show a disease-specific survival benefit with BCT, which consists of lumpectomy plus radiation.
However, experts caution that, as with all observational studies, the evidence is not as strong as that from a prospective randomized trial. Nonetheless, the 10-year breast-cancer-specific survival rates were 94% for patients who underwent BCT, 90% for those who underwent mastectomy alone, and 83% for those who underwent mastectomy plus radiation (P < .001), report the investigators, led by Shailesh Agarwal, MD, from the University of Michigan Medical School in Ann Arbor.
“Many women have the false idea that mastectomy is superior to breast-conserving therapy in terms of survival,” Kandace McGuire, MD, a surgical oncologist from Magee-Womens Hospital of the University of Pittsburgh Medical Center, toldMedscape Medical News.
The Study: Researchers looked at 132,149 patients in the Surveillance, Epidemiology, and End Results (SEER) database who underwent treatment for early-stage disease (tumor size, ≤4 cm; ≤3 positive lymph nodes) from 1998 to 2008. Overall, 70% of the patients were treated with BCT, 27% were treated with mastectomy alone, and 3% were treated with mastectomy plus radiation.
These disease-specific survival findings are in line with findings from a large observational study of patients with early-stage disease in California. That study, by E. Shelley Hwang, MD, from Duke University in Durham, North Carolina, had a median follow-up of 9 years (Cancer. 2013;119:1402-1411).
“I am so happy to see this study, which completely confirms our earlier findings,” said Dr. Hwang. “It is a reassuring message for women [who chose or are considering BCT],” she told Medscape Medical News. The less-invasive BCT was recommended as the treatment of choice for stage I or II disease by the National Institutes of Health (NIH) in 1990.
The NIH recommendation was based on several major randomized trials that showed similar survival rates for BCT and mastectomy. However, those trials are now 40 years old, necessitating more contemporary analyses, the investigators assert. Dr. Agarwal’s team used multivariate analysis to account for possible imbalances in demographic and oncologic data among the treatment groups. They adjusted for variables such as the number of positive lymph nodes (0 vs 1 to 3), tumor size (≤2 cm vs >2 to 4 cm), estrogen-receptor and progesterone-receptor status, and tumor grade.
They found that women undergoing BCT had a higher survival rate than those undergoing mastectomy alone (hazard ratio [HR], 1.31) or mastectomy plus radiation (HR, 1.47). Because of the vagaries of observational data, Dr. Hwang and her colleagues were also cautious when describing their findings.
My Take: For appropriately selected patients with early breast cancer, breast-sparing surgery is preferred to mastectomy, as it spare the breast while not compromising survival (even with long-term follow-up). Six prospective randomized trials (from Europe and the USA) have confirmed this. These prospective, randomized trials provide high level evidence, while the newer findings reported in my blog today are lower evidence, but supportive of the data showing breast conserving management is not inferior to mastectomy-based treatment. I’m Dr. Michael Hunter.
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Reference: JAMA Surg. Published online January 15, 2014.