Bilateral Mastectomy Reduces Cancer Risk Without Improving Survival Rates: Study

A new study presents findings that may influence some women’s choices in breast cancer surgery.

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New research shows that while bilateral mastectomy lowers the risk of cancer in the opposite breast, it doesn’t improve overall survival rates. This finding may influence decisions for women with unilateral breast cancer, challenging the notion that more aggressive surgery yields better long-term outcomes.

Study Details

Researchers at the Women’s College Hospital in Toronto investigated the long-term effects of different surgeries for women with cancer in one breast. They aimed to determine if bilateral mastectomy (removal of both breasts) offers a survival advantage over lumpectomy (removal of tumor and small surrounding area) or unilateral mastectomy (removal of one breast).

Using data from a large cancer registry, the study focused on women diagnosed with early to mid-stage breast cancer in one breast from 2000 to 2019. A total of 661,270 women were included, with an average age of 58.7 years.

The women were divided into three groups based on their initial surgery: lumpectomy, unilateral mastectomy, and bilateral mastectomy. To ensure comparability, 36,028 women in each group were matched by age, tumor stage, and estrogen receptor status.

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Participants were tracked for 20 years to monitor the development of cancer in the opposite breast and breast cancer mortality. Researchers also collected data on treatments such as chemotherapy and radiotherapy.

During the 20-year period, 766 women with lumpectomies, 728 with unilateral mastectomies, and 97 with bilateral mastectomies developed cancer in the opposite breast. Women with bilateral mastectomies had a much lower risk of developing cancer in the opposite breast, with only 1 out of 370 affected, compared to about 1 out of 15 with lumpectomies and 1 out of 50 with unilateral mastectomies.

“We observed similar breast cancer mortality rates in the lumpectomy and bilateral mastectomy patients,” study author and cancer epidemiologist Vasily Giannakeas told The Epoch Times.

Breast cancer mortality rates were 8.54 percent for lumpectomy, 9.07 percent for unilateral mastectomy, and 8.50 percent for bilateral mastectomy.

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The findings indicate that while bilateral mastectomies reduce the risk of contralateral breast cancer, which is when a new cancer appears in the other breast, bilateral mastectomies do not provide a significant survival advantage over lumpectomy or unilateral mastectomy.

“Our goal was to conduct a comprehensive study to provide accurate estimates of these outcomes for each surgical option. We hope our work will give patients and clinicians a better understanding of the risks and aid in the decision-making process when a patient is diagnosed with unilateral breast cancer,” Giannakeas said.

“This study validates what we’re already telling our patients,” Dr. Michelle Sowden, surgical oncologist at the University of Vermont Medical Center, told The Epoch Times.

Medical Professionals Weigh In

In an accompanying editorial, Dr. Seema Khan and Masha Kocherginsky highlight the complexity and heightened risk associated with contralateral breast cancer (CBC). They caution that while the study confirms removing the healthy breast does not improve overall survival, it shows that women who develop cancer in the opposite breast are significantly more likely to die from breast cancer.

According to the study, the 15-year cumulative breast cancer mortality was 32.1 percent for those who developed cancer in the opposite breast, compared to 14.5 percent for those who did not.

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The editorial also addresses the significant differences in the stages of primary cancer and CBC. Some primary cancers are detected at an early stage with minimal risk of death, while some CBCs are diagnosed at an advanced stage with a high risk of death, which can skew the perception of risk and outcomes for patients who develop cancer in the other breast.

They emphasize the ongoing need to educate patients and health care providers about bilateral mastectomies, noting that patient preferences and tolerance for different risks vary widely. Some patients prefer to avoid regular imaging and the potential treatment for a second breast cancer due to the associated risks and quality-of-life issues.

“The education of patients as well as surgeons regarding the risks and benefits of BM [bilateral mastectomy] is a continuing and necessary endeavor given that existing interventions have not impacted the rates of CPM [contralateral prophylactic mastectomy] so far,” they conclude.

Trends in Bilateral Mastectomies

Many women diagnosed with breast cancer opt for double mastectomies. A 2017 study published in the Annals of Surgery reported that the number of women choosing this procedure more than tripled between 2002 and 2012, rising to 12.7 percent from 3.9 percent.

The study analyzed data from 496,488 women with unilateral invasive breast cancer. Despite the increased popularity of double mastectomies during that period, researchers found no significant improvement in long-term survival compared to less extensive surgeries.

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Another 2017 study published in JAMA Surgery found that nearly half of the women diagnosed with early-stage breast cancer considered a double mastectomy and about one in six chose to undergo the procedure. The study, which surveyed 2,578 women, revealed that while 44 percent considered contralateral prophylactic mastectomy, only 38 percent were aware that it does not improve survival for all women.

Recent trends suggest a potential decline, however. More recent research published in the American Journal of Surgery in 2023 further explores these trends. This study found that bilateral mastectomy rates increased from 5.6 percent in 2004 to 15.6 percent in 2013 but have since declined to 11.3 percent in 2020. This decline was consistent across all racial groups, indicating a possible shift in surgical decision-making.

While the initial rise in bilateral mastectomies suggested growing popularity, the recent decrease may reflect increased awareness of the limited survival benefits compared to less extensive surgeries.

Implications for Patients and Health Care Providers

The study’s findings are significant for patients and health care providers. For women diagnosed with unilateral breast cancer, understanding the pros and cons of different surgical options is crucial, Sowden said.

When emotions are running high, newly diagnosed breast cancer patients might find it difficult to absorb this complex information. It seems logical that more aggressive surgery should be better at fighting disease—but that’s not necessarily the case with breast cancer.

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“Education is the most crucial part of the initial visit with a patient. I liken it to myth-busting because many patients believe that removing the breast is safer and will extend their life,” Sowden said. “Patients need to understand the benefits and limitations of surgery. Opting for a mastectomy might seem like a way to eliminate anxiety, but it’s important to know that the recurrence rate isn’t zero.”

Health care providers can use the study results to guide discussions with patients about their treatment options. By emphasizing personalized care, they can help patients weigh the benefits of reduced cancer risk against the lack of survival benefits, leading to more informed decisions aligning with patients’ values and preferences.

Study author Giannakeas shared a personal story to highlight the complexity of surgical decisions. While his study didn’t examine the quality of life related to surgery choice, he noted that other research shows women who choose bilateral mastectomy often feel relieved.

Referring to his mother, diagnosed with breast cancer seven years ago, he said, “Ultimately, she decided to undergo a bilateral mastectomy due to the fear of potentially facing another diagnosis and treatment in the future.” He believes this decision provided her peace of mind that breast-conserving surgery could not.

“Every cancer patient arrives with their own unique set of biases and beliefs, which we need to address for both them and their families. The goal is to ensure that each patient feels confident and comfortable with whatever decision they ultimately make,” Sowden said. “It’s a deeply personal decision, and my role is to support them in making the choice that’s right for them.”