Choosing Between Single vs. Double Mastectomy

Choosing between a single mastectomy and double (bilateral) mastectomy for breast cancer can be challenging, and the right decision is different for each person. Medical concerns to weigh include your risk of developing a second breast cancer, as well as the surgical risk of the procedure.

Personal concerns may include anxiety about lifelong monitoring for another cancer on one side or reduced sensation on the other. There are also financial, emotional, social, and practical issues to consider. Ultimately, the choice is a personal decision that should be made after carefully considering the best information available to date.

This article goes over some of the pros and cons of choosing a single or double mastectomy. It also discusses the benefits and risks of each and survival statistics.

Single Versus Double Mastectomy

For women who have breast cancer in only one breast, the option for those who prefer a mastectomy versus a lumpectomy is to either remove one breast or two. Medically, a “double” or “bilateral” mastectomy refers to the combination of a single or unilateral mastectomy for cancer combined with a “contralateral prophylactic mastectomy” for the breast without cancer.

While the risks and side effects of a double mastectomy are often considered to be twice that of a single mastectomy, there are some differences. While the surgeries are very similar, a sentinel node biopsy or lymph node dissection is not needed on the noncancerous breast, so recovery may be somewhat easier.

Some of the factors that may affect your choice include:

• The benefits and risks of each
• Age at diagnosis
• Genetics
• Stage of cancer
• Future screening
• Cost
• Quality of life
• Personal preference

How Often Women Choose a Single Versus Double Mastectomy

The chance that a woman diagnosed with breast cancer will opt for a double mastectomy (unilateral mastectomy for cancer and contralateral prophylactic mastectomy) has increased significantly over the past few decades.

According to a 2017 study published in the Annals of Surgery, the number of women opting for a double mastectomy tripled between 2002 and 2012, from 3.9% up to 12.7%. Of these women, there was no significant difference in survival.

There was a significant difference, however, in women who chose to have reconstructive surgery, with 48.3% of women who had the double procedure opting for reconstruction compared with only 16% of those who chose a single mastectomy.

Who Opts for a Double Mastectomy?

Younger women tended to choose a double mastectomy more often, with nearly one in four women between the ages of 35 and 45 choosing this approach. Other factors associated with choosing a double mastectomy included more education and being Caucasian.

A 2018 study found that women who have HER2-positive breast cancer were more likely to undergo bilateral mastectomy than those who had tumors that were estrogen receptor-positive but HER2-negative. This isn’t surprising as it’s known that people who have hormone receptor-negative tumors are more likely to develop second primary breast cancer (a second breast cancer unrelated to the first).

Double mastectomies have increased in men as well. According to a 2015 study, the rate of bilateral mastectomy in men with breast cancer rose from 2.2% in 1998 to 11% in 2011.

Hereditary Breast Cancer

Before discussing the medical risks and benefits of a single mastectomy versus double, and quality of life/personal concerns, it’s important to distinguish between people who have hereditary or familial breast cancer.

Many people who have tested positive for a gene mutation that raises breast cancer risk (referred to as previvors) have elected to have a bilateral prophylactic mastectomy before developing breast cancer.

There are a few very important facts to point out, however, when talking about a genetic predisposition to breast cancer. There are currently tests to screen for BRCA mutations and non-BRCA gene mutations that raise breast cancer risk.

Home tests, however, such as 23andMe, are not accurate enough to rule out that risk. These home tests detect only a small fraction of mutations associated with breast cancer risk and are thought to miss roughly 90% of BRCA mutations.

It’s also worth noting that genetic testing for risk is still in its infancy, and even when mutations are not found, women with a strong family history may still be at high risk.

Benefits and Risks

When weighing issues relating to a single versus double mastectomy, it’s important to look at both medical concerns and quality of life or personal concerns. The primary medical concerns relate to the risk of a second cancer and overall survival versus the risks related to the extra surgery involved with a contralateral prophylactic mastectomy.

Survival for Single vs. Double Mastectomy

Several studies have now been done looking at survival in people who opt for a single versus a double mastectomy, and the results have been mixed; some showed improved survival, while others demonstrated little survival benefit.

Since these studies are retrospective (they look back in time), the improvement in survival may be partially attributed to selection bias. Those who were more likely to develop a second cancer they would die from were more likely to have a double mastectomy.

The studies also include different groups of people, for example, only those who have an average risk of a second cancer versus those that include people of both normal and high risk. Since people who have a bilateral mastectomy are more likely to have breast reconstruction (and experience risks related to reconstruction). this is another possible variable.

A double mastectomy does not reduce the risk of recurrence of the original breast cancer.

Rather, a double mastectomy may reduce the risk of a second cancer that could affect survival. So, an important question becomes is a person's risk of developing a second breast cancer worth the risk of extra surgery?

A large 2023 study that included 69,000 women under the age of 40 with unilateral breast cancer found that those who underwent double mastectomy had a five-year breast cancer-specific survival rate of 83.5% compared to 77.7% in those who underwent a single mastectomy. The study also found that women who had a double mastectomy had better overall survival rates than those who had a single mastectomy.

In contrast, a 2014 study published in the Journal of the National Cancer Institute found that the absolute 20-year survival benefit from having a double mastectomy was less than 1%. Contralateral prophylactic mastectomy (double mastectomy) appeared to be more beneficial for young women, those with stage I disease, and those who had estrogen receptor-negative breast cancer. The average predicted life expectancy gain ranged from 0.13 to 0.59 years for women with stage I breast cancer and from 0.08 to 0.29 years with stage II breast cancer.

It’s important to note that these are statistical averages, and women who have stage I disease wouldn’t be expected to live 0.13 to 0.59 years longer if they opted for the double procedure.

Risk of a Second Primary Breast Cancer

Evaluating your risk of a second primary breast cancer (a breast cancer unrelated to your original breast cancer) is often the real issue to look at when trying to decide between a single and double mastectomy.

For women who have familial breast cancer or known gene mutations such as BRCA1 or BRCA2, this risk may be very high. For women without known genetic risk factors, however, the risk can vary depending on age, the receptor status of your breast cancer, and whether you will or have received treatments such as hormonal therapy and/or chemotherapy.

In looking at this risk, it’s helpful to look at the lifetime risk a person of average risk has of developing breast cancer in the first place. At one in eight women, the lifetime risk of breast cancer is roughly 12%.

In contrast, high risk is usually defined as having a lifetime risk greater than 20% or 25%. When a person is at high risk, imaging such as MRI may be recommended for screening, and if the risk is very high, a bilateral prophylactic mastectomy may be considered.

Average Risk of a Second Breast Cancer

The average risk of developing “contralateral breast cancer,” that is, cancer on the breast not originally affected by cancer, is, on average, roughly 0.2% to 0.4% each year. This translates to a 20-year risk of roughly 4% to 8% (though the risk may be lower for women who receive hormonal therapy and/or chemotherapy).

People Who Have a Greater Risk of a Second Breast Cancer

Women and men who have a known BRCA mutation (or other mutations that increase breast cancer risk), as well as those with a strong family history, are at greater risk of developing a second cancer.

Other people who have an elevated risk include:

• Those with estrogen receptor-negative tumors: The risk of contralateral breast cancer is higher with ER-negative than ER-positive tumors at 40% in 10 years.
• Women over age 70: Compared to women under the age of 50, women over the age of 70 have a 47% higher risk of developing contralateral breast cancer over 10 years.
• Women who have had radiation therapy: Women whose first breast cancer was treated with radiation are at increased risk for contralateral breast cancer compared to women whose breast cancer was not treated with radiation.

In some studies, the risk of contralateral breast cancer was also increased for people who had medullary carcinoma, were black versus white, and were over the age of 55 at diagnosis.

Effect of Hormonal Therapy and Chemotherapy on Second Cancer Risk

The risk of developing contralateral breast cancer appears to be significantly lower for people who receive hormonal therapy (for estrogen receptor-positive cancers) or chemotherapy as part of their original treatment. The use of either tamoxifen or an aromatase inhibitor may reduce the risk by 50% to a yearly risk of 0.1% to 0.2%, or a 20-year risk of developing a second cancer of 2% or 4%.

Risk in Women With BRCA and Other Mutations

The 10-year cumulative risk of developing a contralateral breast cancer is 33% for premenopausal people who have a BRCA1 mutation, 27% for BRCA2, and 13% for CHEK2. The risk for people with the PALB2 mutation is 35%, but only if the original tumor was estrogen receptor-negative. The risk isn’t significantly increased in people with the ATM mutation.

Risk in Women With a Strong Family History

A strong family history of breast cancer, even with negative genetic testing, may significantly increase the risk of a second breast cancer. The relative risk, however, varies with the particular family history.

First-degree relatives include parents, siblings, and children, whereas second-degree relatives include grandparents, aunts and uncles, nieces and nephews, and grandchildren. People who have third-degree relatives (cousins or great-grandparents) with breast cancer have very little risk unless there are multiple third-degree relatives with one of these cancers. With five or more affected third-degree relatives, the risk is about 1.3 times that of someone who has no family history.

Certainly, there are many variations in family history among different people with breast cancer, and a careful discussion with your oncologist is important in estimating your individual risk. Talking with a genetic counselor can be very helpful as well.

At the current time, available genetic tests are not able to detect all familial breast cancers.

Detection of Second Breast Cancers

Certainly, an important risk factor for the development of breast cancer is a personal history of breast cancer, and finding a second cancer as early as possible is important. Screening for breast cancer after a single mastectomy is discussed below, but is usually more involved as mammograms can miss up to 20% of breast cancers.

What Happens If Contralateral Breast Cancer Develops?

What happens if a person develops contralateral breast cancer after having a single mastectomy is an important question. Some studies (but not all) suggest that survival is not significantly lower for people who develop contralateral breast cancer.

That said, it’s important to consider what it would mean to you to go through treatment again if the chances of having to do so are small. Some women are very willing to accept a small risk of facing cancer again in exchange for an easier surgery course and retained sensation in their remaining breast, whereas others would forego comfort to lower their risk even more (a prophylactic mastectomy reduces the chance of developing primary breast cancer by 90% or more).

It’s also important to note that some very small early-stage cancers (especially tumors that are HER2 positive) can recur, sometimes as distant metastases.

Surgical Risk

When considering a double versus a single mastectomy, it’s also important to consider the surgical risk related to two mastectomies compared with one.

A double mastectomy (single mastectomy for cancer and contralateral prophylactic mastectomy) takes longer than a single mastectomy, requiring a longer duration of anesthesia. While surgery for breast cancer is generally very safe, there are, at times, complications, especially among people who have risk factors for complications such as underlying heart or lung disease.

There is also a greater potential for complications with a double mastectomy (although these are not necessarily double that of a single mastectomy as a sentinel lymph node biopsy or lymph node dissection is not needed on the noncancerous side). People who have a double mastectomy will usually require a greater number of surgical drains, with a greater risk of postoperative infections, seromas, or hematomas. There is also a greater chance of developing chronic post-mastectomy pain.

Quality of Life and Personal Concerns

In addition to the medical concerns discussed above, the choice to have a single or double mastectomy also involves personal concerns and overall quality of life.

Quality of Life

Studies evaluating the quality of life are mixed. In some, quality of life was better with a single mastectomy, with one finding that people who had a single mastectomy had the equivalent of three months of improved health (over 20 years of follow-up) relative to those who had a double mastectomy.

Other studies have found increased satisfaction in women having double mastectomies. Since reconstruction is more common among women who have double mastectomies, it could be that reconstruction plays a role in quality of life.

Again, it’s important to note that these findings are statistics. Individual people with breast cancer may have strong feelings one way or the other (which in turn influences how they feel following the procedure) and are also influenced by the input (and sometimes experiences) of family and friends.

Future Screening

Both men and women who have a single mastectomy will need to have continued screening for early detection if another breast cancer should develop, whereas women who have had a double mastectomy will not need to undergo breast cancer screening in the future.

Everyone is different in how they feel about this screening, and the degree of scanxiety they experience when scheduling and waiting for results of scans. It’s noteworthy that anxiety regarding follow-up scans can affect family members and friends as well.

Recommendations can vary among different oncologists but may include mammograms or breast MRIs. Mammograms miss roughly 20% of breast cancers and are more likely to miss cancer in dense breasts.

MRI, in contrast, is the most accurate screening test available and is not influenced by dense breasts, but is much more expensive and can be a challenging test for people who are claustrophobic. It’s also now known that the contrast used for breast MRIs, gadolinium, can accumulate in the brain, though it’s not known if this has any clinical significance.

The option of an abbreviated MRI may be an in-between option in the future but is not yet widely available. An abbreviated MRI for breast cancer screening can be done in less than 10 minutes at a cost similar to mammography but with a detection rate similar to MRI.

There is also a chance that a breast biopsy will be needed in the future based on imaging findings.

Sensation

Even with a nipple-sparing/skin-sparing mastectomy, sensation is often markedly reduced following a prophylactic mastectomy. The importance of this and how it relates to sexual health will differ for each person.

Cosmetic Appearance/Symmetry

One traditional argument for a double mastectomy has been to achieve symmetry. Two reconstructed breasts will likely be more symmetrical than one reconstructed or not reconstructed breast and one natural breast. That said, with a single mastectomy and reconstruction, many people will undergo surgery on their non-involved breast to help maintain symmetry.

Costs

While a double mastectomy and reconstruction are usually covered by insurance, there are important cost differences when compared with a single mastectomy.

The cost of a double mastectomy is clearly higher than a single mastectomy. That said, those who have a single mastectomy will require lifelong breast cancer screening on their remaining breasts, and costs associated with that screening.

Studies are again mixed when looking at cost-effectiveness. In one, a single mastectomy plus screening was less costly than a double mastectomy (roughly $6,000 less). Since reconstruction is done more often with a double mastectomy, this cost needs to be considered as well.

On the other hand, another study found that a double mastectomy (single mastectomy for cancer and prophylactic contralateral mastectomy) was less costly than monitoring (yearly or more breast cancer screening) for women younger than age 70. This study, however, included women who had BRCA mutations.

Fortunately, at the current time, a person’s personal choice is considered over cost.

Making a Decision

Clearly, there are many factors to consider when choosing between a single and a double mastectomy. So where do you start?

The first step and primary goal of a double mastectomy is to reduce the risk of second primary breast cancer. It’s thought that many women overestimate this risk so it’s important to have a careful conversation with your healthcare provider (and potentially a genetics counselor) about your unique risk factors.

There are some breast cancer estimator tools available, but none of these include all factors and nuances that may play a role in your risk. This risk should then be weighed against the risk of surgery.

Personal factors are extremely important to evaluate but there isn’t a simple way to do so. Screening after a single mastectomy can cause anxiety, but decreased sensation after a double mastectomy can be very unpleasant for some people in terms of sexuality.

As you make your decision, you may encounter strong opinions on either side from not only family and friends but the medical community as well.

Summary

People who have been diagnosed with breast cancer in only one breast may choose to have a double mastectomy to reduce their chances of developing cancer in the opposite breast. Having a double mastectomy may help reduce your risk but it also comes with increased surgical risk and financial, emotional, and practical considerations.

Whether or not having a double mastectomy for unilateral breast cancer improves survival is still an open question. Some studies show significant improvement in survival, while others show minimal improvement. Ultimately the choice to have this procedure is a personal one that you should discuss carefully with your healthcare provider.