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ORLANDO -- The decision by women with breast cancer to undergo lumpectomy rather than mastectomy appears to be a safer choice than previously believed, researchers reported.

Data from nine clinical trials over the last decade and a half show that compared with for historic protocols, use of modern multi-modality lumpectomy significantly reduced breast cancer recurrence at the original tumor site.

Specifically, the researchers found a 4.2% local recurrence rate for women who had lumpectomy and modern-era chemotherapy or other systemic therapies along with radiation therapy. This compares favorably with the "generally accepted" 5-10% rate for lumpectomy recurrence, said Heather Neuman, MD, of the University of Wisconsin School of Medicine and Public Health, who presented the findings at the .

Speaking at a news conference at the meeting, Neuman pointed out that while the survival rates for both lumpectomy and mastectomy are similar, women have had a difficult choice between the two because of the greater risk of local recurrence with lumpectomy. However, she explained, the historical data on local recurrence with lumpectomy is based on older treatment protocols and over the last decade breast cancer therapies have become more personalized -- and more effective -- for a patient's particular disease profile.

Neuman and her colleagues therefore sought to evaluate the recurrence rates after lumpectomy in a cohort of patients who had received modern-era therapy. Accordingly, the team evaluated data from nine Alliance for Clinical Trials in Oncology legacy clinical trials that included 6,927 women with stages I-III breast cancer between 1997 and 2011.

The researchers used Kaplan-Meier curves to estimate 5-year rates of local recurrence and used multivariable Cox proportional hazards models to identify factors associated with time to local recurrence, such as age, tumor size, node status, and molecular tumor subtype.

The overall rate of local recurrence at 5 years was 4.2% (95% CI 3.7-4.8%). There were variations seen based on receptor type, with the lowest rates seen for triple-positive patients that are ER/PR positive and HER2 positive (3%, 95% CI 1.9-4.8%). The team also found that the highest rates were for patients with ER/PR- HER2neu- (6.9%, 95% CI 5.6-8.4%).

"When looking at the Cox model that controlled for age, tumor size, and nodal status, receptor type remained very strongly associated with local recurrence," Neuman said. "Additionally, older age was associated with a lower risk of local recurrence, and more positive nodes were associated with a higher risk of local recurrence."

The study demonstrates "that in the modern era, the rate of local recurrence after breast-conserving surgery is quite low -- lower than what has often been used historically to counsel women. These modern-era estimates should be used to inform discussions between patients and surgeons regarding the decision between breast conservation and mastectomy."

Neuman also noted that as the knowledge of breast cancer biology grows, it has led to advances in breast-conservation therapies, such as more effective radiation therapy -- which, she believes, has had the biggest impact on preventing tumor recurrence.

"By analyzing a large group of patients treated in the modern era, this study provides physicians with more current information to provide patients regarding local recurrence rates following breast-conserving therapy," observed , medical director of Breast Surgical Oncology at Indiana University School of Medicine in Indianapolis, who was not involved in the study. "Encouragingly, [the researchers] note very low recurrence rates with variability by receptor status.

"These findings, along with the recent changes in the American Joint Committee on Cancer staging, further emphasize the importance of biologic factors in patient outcomes. Additionally, the study provides support for patients choosing breast-conserving therapy who are treated with modern, multimodal therapy."