Table of ContentsView AllTable of ContentsClassificationSymptomsCauses and Risk FactorsDiagnosisPrognosis

Table of ContentsView All

View All

Table of Contents

Classification

Symptoms

Causes and Risk Factors

Diagnosis

Prognosis

Bilateral breast cancer is when tumors develop in both breasts of the same patient. Compared to unilateral (one side) breast cancer cases, bilateral breast cancer patients tend to be younger and the tumors smaller and of an earlier stage at diagnosis.

According to the Surveillance, Epidemiology, and End Results (SEER) database (1973–2014), bilateral cancers occurred in 1.4% of breast cancer patients in 1975 to 2.9% in 2014.

Other data sets show the incidence range of 1%–11% of breast cancer patients, depending on how the cases are defined and the time period of surveillance. It is difficult to know how often this type of cancer actually occurs because there isn’t optimal evidence differentiating between women who have had one or two primary cancers.

Unfortunately, data are limited on how to best manage bilateral breast cancer, what the best treatments are, and prognosis (outcome). However, it is a relatively uncommon cancer.

Breast Cancer Overview

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A middle-aged, mixed race woman, sits on an exam table in a doctors office.

Bilateral breast cancers are categorized as follows as synchronous and asynchronous, or metachronous:

Both cancers are consideredprimarycancers and not one that hasmetastasized(spread).

Metastatic Breast Cancer

Symptoms of synchronous bilateral breast cancer consists of cancer signs and symptoms in both breasts. Symptoms may include:

Symptoms of Breast Cancer

There is little known about the risk factors for bilateral breast cancer. Some research indicates that possible risk factors include:

Hormone Receptor Status in Breast Cancer

There may also be some factors that help protect patients from developing bilateral breast cancer. These include:

Traditional risk factors for breast cancer that do not seem to increase risk for bilateral breast cancer include cigarette smoking, hormone replacement therapy, or oral contraceptives.

Diagnosis of synchronous bilateral breast cancer is based on signs and symptoms of cancer in both breasts.At the time of physical examination, the cancer may not be noticeable in both breasts. If cancer is detected in one breast, standard practice is to follow up with a bilateralmammography, which may detect signs of cancer in the opposite breast (asynchronous bilateral breast cancer).

While mammography is the standard screening tool for breast cancer, mammography also has its limitations. Mammograms vary in sensitivity and have been shown to miss detection of bilateral breast cancer. In one study, the mammography detected only 19% of bilateral breast cancers compared with 72.7% of unilateral breast cancers.

If you believe you are at high risk, speak with your doctor about screening for bilateral breast cancer.

What Is a Breast MRI?

Treatment

There are several treatments that can potentially reduce the risk of developing cancer in the opposite breast, such as:

Considerations for Bilateral MastectomyIncreasingly, women with unilateral breast cancer are treated with bilateral mastectomy (removal of both breasts). The reason is to stop the risk of death from developing bilateral breast cancer, or cancer in the opposite breast. However, this treatment is controversial because bilateral mastectomy is not proven to decrease death from breast cancer.It’s important to speak with your healthcare provider and assess your risk of developing bilateral breast cancer and whether this surgical intervention is warranted.

Considerations for Bilateral Mastectomy

Increasingly, women with unilateral breast cancer are treated with bilateral mastectomy (removal of both breasts). The reason is to stop the risk of death from developing bilateral breast cancer, or cancer in the opposite breast. However, this treatment is controversial because bilateral mastectomy is not proven to decrease death from breast cancer.It’s important to speak with your healthcare provider and assess your risk of developing bilateral breast cancer and whether this surgical intervention is warranted.

Increasingly, women with unilateral breast cancer are treated with bilateral mastectomy (removal of both breasts). The reason is to stop the risk of death from developing bilateral breast cancer, or cancer in the opposite breast. However, this treatment is controversial because bilateral mastectomy is not proven to decrease death from breast cancer.

It’s important to speak with your healthcare provider and assess your risk of developing bilateral breast cancer and whether this surgical intervention is warranted.

Choosing Between Single vs. Double Mastectomy

There is conflicting evidence about the survival rate for bilateral breast cancer. Some reports suggest higher mortality when compared with unilateral breast cancer, while others report similar survival rates.

A 2007 study of a Swedish population of women analyzed the difference in prognosis between synchronous and metachronous bilateral breast cancer. It found that women were 3.9 times more likely to die of metachronous bilateral breast cancer compared with women with unilateral breast cancer if:

However, the same study found that if women develop bilateral breast cancer more than 10 years after the first diagnosis, they have a similar prognosis as women with unilateral breast cancer.

A 2018 study suggests that developing synchronous bilateral breast cancer has a worse prognosis and higher mortality rate than unilateral breast cancer as a result of having simultaneous cancers.

A Word From Verywell

Despite the limited and conflicting evidence on the treatment and prognosis for bilateral breast cancer, it is still a relatively uncommon diagnosis. If you believe you are at risk, speak with your doctor about screening for bilateral breast cancer. Early detection and tailored treatment will improve your prognosis.

11 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Kheirelseid EAH, Jumustafa H, Miller N, et al.Bilateral breast cancer: analysis of incidence, outcome, survival and disease characteristics.Breast Cancer Res Treat. 2011;126(1):131-140. doi:10.1007/s10549-010-1057-ySakai T, Ozkurt E, DeSantis S, et al.National trends of synchronous bilateral breast cancer incidence in the United States.Breast Cancer Res Treat. 2019;178(1):161-167. doi:10.1007/s10549-019-05363-0Jobsen JJ, van der Palen J, Ong F, Riemersma S, Struikmans H.Bilateral breast cancer, synchronous and metachronous; differences and outcome.Breast Cancer Res Treat. 2015;153(2):277-283. doi:10.1007/s10549-015-3538-5Narod SA.Bilateral breast cancers.Nat Rev Clin Oncol. 2014;11(3):157-166. doi: 10.1038/nrclinonc.2014.3Mejdahl MK, Wohlfahrt J, Holm M, et al.Breast cancer mortality in synchronous bilateral breast cancer patients.Br J Cancer. 2019;120(7):761-767. doi: 10.1038/s41416-019-0403-zAmerican Cancer Society.Breast Cancer Signs and Symptoms.Beckmann KR, Buckingham J, Craft P, et al.Clinical characteristics and outcomes of bilateral breast cancer in an Australian cohort.The Breast. 2011;20(2):158-164. doi:10.1016/j.breast.2010.10.004Setz-Pels W, Duijm LEM, Groenewoud JH, et al.Detection of bilateral breast cancer at biennial screening mammography in the Netherlands: a population-based study.Radiology. 2011;260(2):357-363. doi:10.1148/radiol.11102117Goss PE.Letrozole in the extended adjuvant setting: MA.17.Breast Cancer Res Treat. 2007;105(1):45-53. doi:10.1007/s10549-007-9698-1Schaapveld M, Visser O, Louwman WJ, et al.The impact of adjuvant therapy on contralateral breast cancer risk and the prognostic significance of contralateral breast cancer: a population based study in the Netherlands.Breast Cancer Res Treat. 2008;110(1):189-197. doi: 10.1007/s10549-007-9709-2Hartman M, Czene K, Reilly M, et al.Incidence and prognosis of synchronous and metachronous bilateral breast cancer.JCO. 2007;25(27):4210-4216. doi:10.1200/JCO.2006.10.5056

11 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Kheirelseid EAH, Jumustafa H, Miller N, et al.Bilateral breast cancer: analysis of incidence, outcome, survival and disease characteristics.Breast Cancer Res Treat. 2011;126(1):131-140. doi:10.1007/s10549-010-1057-ySakai T, Ozkurt E, DeSantis S, et al.National trends of synchronous bilateral breast cancer incidence in the United States.Breast Cancer Res Treat. 2019;178(1):161-167. doi:10.1007/s10549-019-05363-0Jobsen JJ, van der Palen J, Ong F, Riemersma S, Struikmans H.Bilateral breast cancer, synchronous and metachronous; differences and outcome.Breast Cancer Res Treat. 2015;153(2):277-283. doi:10.1007/s10549-015-3538-5Narod SA.Bilateral breast cancers.Nat Rev Clin Oncol. 2014;11(3):157-166. doi: 10.1038/nrclinonc.2014.3Mejdahl MK, Wohlfahrt J, Holm M, et al.Breast cancer mortality in synchronous bilateral breast cancer patients.Br J Cancer. 2019;120(7):761-767. doi: 10.1038/s41416-019-0403-zAmerican Cancer Society.Breast Cancer Signs and Symptoms.Beckmann KR, Buckingham J, Craft P, et al.Clinical characteristics and outcomes of bilateral breast cancer in an Australian cohort.The Breast. 2011;20(2):158-164. doi:10.1016/j.breast.2010.10.004Setz-Pels W, Duijm LEM, Groenewoud JH, et al.Detection of bilateral breast cancer at biennial screening mammography in the Netherlands: a population-based study.Radiology. 2011;260(2):357-363. doi:10.1148/radiol.11102117Goss PE.Letrozole in the extended adjuvant setting: MA.17.Breast Cancer Res Treat. 2007;105(1):45-53. doi:10.1007/s10549-007-9698-1Schaapveld M, Visser O, Louwman WJ, et al.The impact of adjuvant therapy on contralateral breast cancer risk and the prognostic significance of contralateral breast cancer: a population based study in the Netherlands.Breast Cancer Res Treat. 2008;110(1):189-197. doi: 10.1007/s10549-007-9709-2Hartman M, Czene K, Reilly M, et al.Incidence and prognosis of synchronous and metachronous bilateral breast cancer.JCO. 2007;25(27):4210-4216. doi:10.1200/JCO.2006.10.5056

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

Kheirelseid EAH, Jumustafa H, Miller N, et al.Bilateral breast cancer: analysis of incidence, outcome, survival and disease characteristics.Breast Cancer Res Treat. 2011;126(1):131-140. doi:10.1007/s10549-010-1057-ySakai T, Ozkurt E, DeSantis S, et al.National trends of synchronous bilateral breast cancer incidence in the United States.Breast Cancer Res Treat. 2019;178(1):161-167. doi:10.1007/s10549-019-05363-0Jobsen JJ, van der Palen J, Ong F, Riemersma S, Struikmans H.Bilateral breast cancer, synchronous and metachronous; differences and outcome.Breast Cancer Res Treat. 2015;153(2):277-283. doi:10.1007/s10549-015-3538-5Narod SA.Bilateral breast cancers.Nat Rev Clin Oncol. 2014;11(3):157-166. doi: 10.1038/nrclinonc.2014.3Mejdahl MK, Wohlfahrt J, Holm M, et al.Breast cancer mortality in synchronous bilateral breast cancer patients.Br J Cancer. 2019;120(7):761-767. doi: 10.1038/s41416-019-0403-zAmerican Cancer Society.Breast Cancer Signs and Symptoms.Beckmann KR, Buckingham J, Craft P, et al.Clinical characteristics and outcomes of bilateral breast cancer in an Australian cohort.The Breast. 2011;20(2):158-164. doi:10.1016/j.breast.2010.10.004Setz-Pels W, Duijm LEM, Groenewoud JH, et al.Detection of bilateral breast cancer at biennial screening mammography in the Netherlands: a population-based study.Radiology. 2011;260(2):357-363. doi:10.1148/radiol.11102117Goss PE.Letrozole in the extended adjuvant setting: MA.17.Breast Cancer Res Treat. 2007;105(1):45-53. doi:10.1007/s10549-007-9698-1Schaapveld M, Visser O, Louwman WJ, et al.The impact of adjuvant therapy on contralateral breast cancer risk and the prognostic significance of contralateral breast cancer: a population based study in the Netherlands.Breast Cancer Res Treat. 2008;110(1):189-197. doi: 10.1007/s10549-007-9709-2Hartman M, Czene K, Reilly M, et al.Incidence and prognosis of synchronous and metachronous bilateral breast cancer.JCO. 2007;25(27):4210-4216. doi:10.1200/JCO.2006.10.5056

Kheirelseid EAH, Jumustafa H, Miller N, et al.Bilateral breast cancer: analysis of incidence, outcome, survival and disease characteristics.Breast Cancer Res Treat. 2011;126(1):131-140. doi:10.1007/s10549-010-1057-y

Sakai T, Ozkurt E, DeSantis S, et al.National trends of synchronous bilateral breast cancer incidence in the United States.Breast Cancer Res Treat. 2019;178(1):161-167. doi:10.1007/s10549-019-05363-0

Jobsen JJ, van der Palen J, Ong F, Riemersma S, Struikmans H.Bilateral breast cancer, synchronous and metachronous; differences and outcome.Breast Cancer Res Treat. 2015;153(2):277-283. doi:10.1007/s10549-015-3538-5

Narod SA.Bilateral breast cancers.Nat Rev Clin Oncol. 2014;11(3):157-166. doi: 10.1038/nrclinonc.2014.3

Mejdahl MK, Wohlfahrt J, Holm M, et al.Breast cancer mortality in synchronous bilateral breast cancer patients.Br J Cancer. 2019;120(7):761-767. doi: 10.1038/s41416-019-0403-z

American Cancer Society.Breast Cancer Signs and Symptoms.

Beckmann KR, Buckingham J, Craft P, et al.Clinical characteristics and outcomes of bilateral breast cancer in an Australian cohort.The Breast. 2011;20(2):158-164. doi:10.1016/j.breast.2010.10.004

Setz-Pels W, Duijm LEM, Groenewoud JH, et al.Detection of bilateral breast cancer at biennial screening mammography in the Netherlands: a population-based study.Radiology. 2011;260(2):357-363. doi:10.1148/radiol.11102117

Goss PE.Letrozole in the extended adjuvant setting: MA.17.Breast Cancer Res Treat. 2007;105(1):45-53. doi:10.1007/s10549-007-9698-1

Schaapveld M, Visser O, Louwman WJ, et al.The impact of adjuvant therapy on contralateral breast cancer risk and the prognostic significance of contralateral breast cancer: a population based study in the Netherlands.Breast Cancer Res Treat. 2008;110(1):189-197. doi: 10.1007/s10549-007-9709-2

Hartman M, Czene K, Reilly M, et al.Incidence and prognosis of synchronous and metachronous bilateral breast cancer.JCO. 2007;25(27):4210-4216. doi:10.1200/JCO.2006.10.5056

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