Young women with breast cancer often opt for mastectomy over breast-conserving surgery. But a new study shows that even for those with high-risk disease, more extensive surgery does not seem to prevent recurrences or extend survival.

In the US, younger women with early-stage breast cancer have long had higher rates of mastectomy, including bilateral mastectomy, versus those older than 50. That's despite studies showing no long-term survival advantage with more extensive surgery.

The new findings, presented recently at the annual meeting of the American Society of Breast Surgeons (ASBrS), are in line with prior research. And they extend those results specifically to young women with locoregionally advanced, high-risk breast cancer undergoing neoadjuvant therapy.

The basic takeaway is that younger age should not preclude those patients from having breast-conserving surgery, according to lead researcher Jennifer Tseng, MD, of City of Hope Orange County, in Irvine, California.

"We know, at least, that it is safe to recommend both surgery approaches for younger women," she said.

Different Surgeries, Similar Outcomes

The findings are based on data from the I-SPY2 trial, involving patients with stage II or III breast cancer and high-risk MammaPrint scores. Tseng's team focused on 1737 patients enrolled between 2010 and 2022; 698 were aged 45 years or younger and 1039 were older than 45. 

Overall, the researchers found, younger patients had a greater tumor burden than older patients, both before and after neoadjuvant systemic therapy. But there were no differences between the age groups in terms of tumor subtype, nodal status, and histologic grade.

In keeping with past studies, younger patients were significantly less likely to undergo breast-conserving surgery — at just under 37%, vs 48.5% of women older than 45.

However, there was no evidence that more extensive surgery improved younger women's outcomes, Tseng reported during an ASBrS press briefing.

At a median of just over 5 years, there were 80 deaths and 58 local recurrences among women aged 45 or younger. And after adjustment for tumor subtype, clinical T category, nodal status, grade, and residual cancer burden, there were no significant differences in overall survival or recurrence between young women who had breast-conserving surgery and those who underwent mastectomy.

A sub-analysis of women younger than 40 yielded similar results, Tseng noted.

Signs of Change

The study did find that surgery trends shifted over time. Among younger women, breast-conserving surgery increased from 29% in 2010 to 50% by 2022. That appeared to coincide with improved responses to neoadjuvant medical therapy, Tseng said: Those patients with less disease left over after medical treatment were the ones with increasing rates of breast-conserving therapy.

Tina Heiken, MD, chair of the ASBrS Annual Meeting Scientific Committee, highlighted that point.

"It's nice to see that we've developed some equipoise with advances in systemic therapies to permit young women to preserve their breasts," she said during the press briefing.

At the same time, Tseng said there's a need to better understand why mastectomy rates remain higher among younger women.

In addition to the lack of survival benefit, she noted that more extensive surgery carries greater risks, including permanent loss of chest wall sensation, body image and self-esteem issues, impact on sexual well-being and arousal, and mobility issues.

Still, women with breast cancer may opt for more surgery even when they know there's no evidence it will extend their lives. As previously reported by Medscape, women who choose double mastectomy often cite other reasons — including their desire to avoid the mental and financial toll of ongoing screenings and potential biopsies, and an aesthetic preference for breast symmetry.

"Patient anxiety and worry are very much reasons young women may think about more extensive breast surgery," Tseng told Medscape.

Unfortunately, she said, her study couldn't dig into the factors that influenced patient-physician decisions on surgery type. The researchers also lacked information on whether mastectomies were unilateral or bilateral.

"Many reasons drive the decision for surgery," Tseng said, adding that "we were hoping to at least demonstrate that young age should not solely be used to choose breast conservation or mastectomy."

Tseng reported financial relationships with Intuitive Surgical. Heiken reported research funding from Genentech and SkylineDX BV. 

Sharon Worcester, MA, is an award-winning medical journalist based in Birmingham, Alabama, writing for Medscape, MDedge, and other affiliate sites. She currently covers oncology, but she has also written on a variety of other medical specialties and healthcare topics. She can be reached at sworcester@mdedge.com or on X: @SW_MedReporter.