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SAN FRANCISCO -- Lumpectomy doesn't carry higher recurrence or mortality risk than mastectomy for young women with breast cancer, two separate studies found.

Loco-regional recurrence was nearly identical over a median six years of follow-up at 7.34% with breast conserving surgery and 7.40% with mastectomy (P=0.980) in a single-center study reported by Julliette M. Buckley, MD, of Massachusetts General Hospital in Boston, and colleagues.

And there were no significant differences between the two surgical approaches for early-stage breast cancer on any measure of overall or breast cancer-specific survival in a national study by Usama Mahmood, MD, of the MD Anderson Cancer Center in Houston, and colleagues.

Both studies of outcomes for women 40 and younger were presented at a press telebriefing in advance of presentation at the Multidisciplinary Breast Cancer Symposium here.

More recent advances in therapy appear to have made lumpectomy a "safe option" for young women, Buckley's group suggested.

The conventional wisdom has been that young women with breast cancer need mastectomy, noted the moderator of the telebriefing, Andrew D. Seidman, MD, of Memorial Sloan-Kettering Cancer Center in New York City.

And indeed, the growing trend toward mastectomy in younger women appears to be driven by worries about recurrence, which prior studies suggested was a greater risk with lumpectomy, Buckley explained.

One study reported in the Journal of Clinical Oncology last year showed rising mastectomy rates in all age groups but the highest rates and greatest growth was among 18- to 39-year-olds.

In Mahmood's analysis of the national Surveillance, Epidemiology, and End Results (SEER) database from 1990 through 2007, 55% of women ages 20 to 39 opted for mastectomy.

None of the speakers at the telebriefing expressed optimism that these two studies alone would reverse that trend.

Buckley suggested that the data could help young women with breast cancer make a more informed choice, but its biggest impact will likely be in making them "feel safe and secure keeping their own breast" if they choose lumpectomy.

The studies should be "reassuring to younger women that young age alone does not seem to mandate the need for mastectomy," Seidman agreed in the press briefing.

Other factors, such as BRCA mutation status, which neither study accounted for, should also play a role in the surgical decision, he noted.

That genetic risk awareness as well as use of MRI for screening younger women and improvements in systemic and radiation therapy have boosted survival for young women with breast cancer, giving them a good prognosis, Buckley told reporters.

In her group's study of 628 women diagnosed with breast cancer from 1996 through 2008, local recurrence rates overall were 5.6% at five years and 13% at 10 years.

Those rates were lower than in prior studies, Buckley's group noted.

Mahmood's study included 14,760 women with early-stage breast cancer in the SEER database followed for a median of 5.7 years.

After adjustment for all available tumor and patient characteristics, lumpectomy and mastectomy came out similar for overall survival and for breast cancer-specific survival (both HR 0.93, P=0.16 and P=0.26, respectively).

In a matched-pair analysis of more than 4,600 women, the same was true for lumpectomy and mastectomy:

• 10-year overall survival rates were 83.5% versus 83.6% (P=0.99)
• 10-year breast cancer-specific survival rates were 85.5% for both groups (P=0.88)

"Women should be counseled appropriately regarding their treatment options and should not choose a mastectomy based on an assumption of improved survival," Mahmood concluded in the briefing.

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