Choosing Between Single vs. Double Mastectomy

Weighing the risks and benefits of a contralateral prophylactic mastectomy

Choosing between a single mastectomy and double (bilateral) mastectomy for breast cancer can be challenging, and the right decision is different for each woman. 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.

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 (a double or bilateral mastectomy). Medically, a "double" mastectomy refers to the combination of a single mastectomy (unilateral) for cancer combined with a contralateral prophylactic mastectomy for the breast without cancer.

It's important to note that 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 are not needed on the non-cancerous breast, so recovery may be somewhat easier.

Breast cancer is the most common cause of cancer in women and the second leading cause of cancer-related deaths. Since it's thought to affect roughly one in eight women during her lifetime, many people will be called upon to make this decision.

The benefits and risks, as well as the pros and cons of either a single or double mastectomy, will be discussed in greater depth, but some of the factors that may affect your choice include:

  • 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?

Women who are younger tended to choose a double mastectomy more often, with nearly one in four younger women choosing this approach.

Other factors associated with choosing a double mastectomy included more education and being Caucasian. In addition, double mastectomies were chosen more often among women in the United States than in Berlin, Germany or Seoul, South Korea.

With regard to tumor type, 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.

Hereditary breast cancer is one situation in which the benefits of a double mastectomy likely outweighs the risks.

After all, a number of 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 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

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 with others showing 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.

It's important to note that survival from the current breast cancer is not affected by the choice of procedure.

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?

An oft-quoted 2010 study published in the Annals of Surgical Oncology found that a double mastectomy (unilateral mastectomy for cancer and contralateral prophylactic mastectomy) was associated with a 10-year survival rate of 84% versus 74% in the single mastectomy group. In this study, a double mastectomy was associated with not only a lower incidence of a second breast cancer in the other (contralateral) breast, but with improved overall and disease-free survival after controlling for (removing variables based on) age, family history, stage of the cancer, receptor status, chemotherapy, radiation therapy, and hormonal therapy.

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%, but 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.

The prevailing thought at this time for women who do not have known genetic risk factors or strong family history is that the survival benefits from having a double mastectomy—if present—is relatively low.

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 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.

Among women who have had breast cancer and develop a second cancer, breast cancer is responsible for 30% to 50% of those cancers.

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 somewhat higher with ER-negative than ER-positive tumors at 0.2% to 0.65% each year, or 12% at 20 years.
  • Women who are less than 50: Women who are under the age of 50 have a higher average risk of developing a contralateral breast cancer at roughly 11% over 20 years. These women are also likely to have a longer lifespan and therefore, a longer period of time during which they might develop a second breast cancer.
  • Women who have had previous chest radiation, such as for lymphomas

In some studies, the risk of contralateral breast cancer was also increased for people who had medullary carcinoma, were black versus white, received radiation therapy, 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 risk of developing a contralateral breast cancer for people who have a BRCA mutation is roughly 3% each year, or 60% over a period of 20 years.

The risk of a contralateral breast cancer with other mutations (such as PALB2 or CHEK2) is currently unknown.

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.

Those who have first-degree relatives with breast or ovarian cancer, especially when diagnosed at an early age (less than age 50), a combination of first-degree and second-degree relatives, or several second-degree relatives with these cancers, carry the highest risk of developing contralateral breast cancer.

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 or ovarian cancer carry a risk roughly 1.5 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, genetic tests that are available 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 15 percent of breast cancers.

What Happens if a Contralateral Breast Cancer Develops?

What happens if a person develops a 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 a 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 breast cancer by 94%).

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 non-cancerous 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.

A 2018 study found that having a double mastectomy increased the average hospital stay to three days in contrast to two days, but no difference was noted in 90-day reoperation rates.

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 followup) 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 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 followup 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 15% 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 MRI's, gadolinium, can accumulate in the brain, though it's not known if this has any clinical significance.

The option of fast may be an in-between option in the future, but is not yet widely available. A fast (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 $5,000 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 doctor (and potentially a genetic 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 (breasts aren't vital but do have a role in sexual health) can be very unpleasant for some people.

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

It's alright to disagree with the opinions of some providers as long as you are making an educated choice based on the best information possible, while realizing that said information is incomplete at this time.

A Word From Verywell

There are reasons both for and against having a double mastectomy, but the bottom line is that it is a personal choice. Some people prefer preserving a healthy breast by having a single mastectomy, and others wish to reduce their risk of a second breast cancer, even if that risk is small.

When making a decision you may have friends or family who strongly suggest that you choose one option or another, but it's important to make the choice that works best for you, not someone else. Learn about the pros and cons of each approach in order to make an educated decision, and then honor yourself by making the choice that feels best for you alone.

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