What are the indications for bilateral mastectomy?

Indications for Bilateral Mastectomy

Bilateral mastectomy is indicated for women with BRCA1/2 mutations, prior chest wall irradiation for lymphoma, bilateral malignant breast masses, or contralateral risk-reducing surgery in select high-risk breast cancer patients—achieving a 90-95% reduction in breast cancer incidence and mortality. 1

Risk-Reducing (Prophylactic) Bilateral Mastectomy

Genetic High-Risk Populations

BRCA1/2 Mutation Carriers:

• Women with confirmed BRCA1 or BRCA2 pathogenic variants should be offered bilateral risk-reducing mastectomy after careful genetic assessment and mandatory psychological counseling. 1
• BRCA1 carriers face a lifetime breast cancer risk of 65-90%, with a 10-year actuarial risk of contralateral breast cancer of 25-31%. 1
• Bilateral mastectomy reduces both breast cancer incidence and mortality by 90-95%. 1, 2, 3
• The number needed to treat with risk-reducing mastectomy to prevent one breast cancer case is 6 in high-risk women. 1
• Age and life expectancy must be considered during counseling, as breast cancer risk remains elevated throughout life in mutation carriers. 1

Prior Chest Wall Irradiation:

• Women with history of thoracic radiation for Hodgkin lymphoma at a young age have a 56.7-fold increased breast cancer risk and should be offered bilateral risk-reducing mastectomy. 1
• The cumulative absolute risk of breast cancer at age 55 is 29% for women treated at age 25 with 40 Gy radiation. 1

TP53 and PTEN Mutation Carriers:

• Women with confirmed TP53 or PTEN mutations should be offered bilateral risk-reducing mastectomy as part of their high-risk management. 1

Surgical Technique for Risk-Reducing Mastectomy

• Total mastectomy with removal of all breast tissue is required—subcutaneous mastectomy alone is insufficient. 1, 4, 5
• Axillary lymph node dissection is not required unless breast cancer is identified on pathologic evaluation of the mastectomy specimen. 1
• Immediate breast reconstruction should be discussed with all patients and is appropriate for most. 1, 4, 5
• Nipple-sparing mastectomy may be safe and effective for BRCA1/2 carriers, though longer follow-up data are needed. 1

Therapeutic Bilateral Mastectomy

Bilateral Malignant Breast Masses

Confirmed Bilateral Breast Cancer:

• Bilateral total mastectomy with sentinel lymph node biopsy for each breast is the standard surgical approach when bilateral malignancy is confirmed. 4, 5
• Each breast lesion requires independent pathologic confirmation via core needle biopsy before surgery. 4, 6
• Complete pathologic assessment must include histological type/grade, ER/PR status, HER2 status, and Ki67 for both tumors. 4, 6
• Genetic counseling is mandatory given the bilateral presentation, particularly to assess for BRCA1/2 mutations. 4, 5
• Never perform unilateral mastectomy when bilateral malignancy is confirmed—the risk is equal in both breasts. 4, 5

Bilateral Breast Conservation Alternative:

• Breast conservation therapy is feasible for bilateral disease only when ALL criteria are met: clear surgical margins achievable in both breasts, appropriate tumor-to-breast size ratio, absence of multicentric disease, no prior chest wall irradiation, and patient can tolerate mandatory bilateral whole breast radiation. 4
• Bilateral whole breast radiation therapy is absolutely mandatory if breast conservation is chosen—omitting radiation results in unacceptably high local recurrence rates. 4

Contralateral Risk-Reducing Mastectomy in Unilateral Breast Cancer

High-Risk Pathologic Features:

• Contralateral risk-reducing mastectomy may be considered for women with unilateral breast cancer who have: multifocal lobular carcinoma, invasive carcinoma associated with widespread LCIS, or hyperplasia with atypia in surrounding breast tissue. 1
• The average annual risk of contralateral breast cancer is approximately 0.5% in the general breast cancer population, but increases to 3% in BRCA1/2 mutation carriers. 7

Patient-Requested Contralateral Mastectomy:

• Increasing numbers of younger women with unilateral breast cancer are requesting bilateral mastectomy despite no proven survival advantage over breast conservation. 1
• These patients must be properly counseled that early-stage breast cancer patients who choose breast conservation may have equal or better outcomes compared to mastectomy. 1, 4
• Contralateral mastectomy has not been proven to reduce mortality from breast cancer, though benefit may not become apparent until the second decade after treatment. 7

In Situ Malignancy Considerations

Ductal Carcinoma In Situ (DCIS):

• DCIS may be treated with total mastectomy or breast-conserving therapy with clear margins. 1
• Sentinel lymph node biopsy is not routinely required for pure DCIS but may be reasonable for large and/or high-grade tumors requiring mastectomy (in case incidental invasive cancer is found). 1
• The invasive breast cancer underestimation rate with DCIS is 20-38%, increasing with palpable mass, associated density on mammogram, poorly differentiated DCIS, younger age, and larger extent of microcalcifications. 1

Lobular Neoplasia (LCIS):

• LCIS is a non-obligate precursor to invasive cancer and a risk factor for future bilateral breast cancer (relative risk 5.4-12). 1
• Bilateral mastectomy is not a recommended approach for most women with LCIS without additional risk factors, though it may be considered for highly selected patients who request it. 1
• The pleomorphic variant of lobular neoplasia may behave similarly to DCIS and should be treated accordingly after multidisciplinary discussion. 1

Critical Counseling Points and Pitfalls

Pre-Surgical Requirements:

• Multidisciplinary consultations are mandatory before bilateral mastectomy, including discussions of risks, benefits, and breast reconstruction options. 1
• Clinical breast examination and bilateral mammogram must be performed within 6 months before risk-reducing mastectomy. 1
• Careful genetic assessment and psychological counseling are mandatory before undertaking risk-reducing surgery. 1

Psychosocial Considerations:

• Patients are generally satisfied with their decision for risk-reducing mastectomy, with reported decreases in worry about breast cancer. 1
• Negative impacts on body image and sexuality have been reported and should be discussed. 1
• Long-term physical symptoms include lower sensitivity to touch, pain, tingling, infection, and edema. 1

Common Pitfalls to Avoid:

• Do not automatically recommend bilateral mastectomy simply because disease is bilateral—this represents overtreatment in appropriately selected breast conservation candidates. 4
• Do not omit genetic counseling in bilateral breast cancer, as this presentation strongly suggests possible hereditary cancer syndrome. 4, 5
• Never counsel patients that mastectomy provides superior survival to breast conservation in early-stage disease—outcomes may be equal or better with breast conservation when properly selected. 4
• Do not delay tissue biopsy, as this delays treatment of malignancy. 4, 5

Post-Mastectomy Surveillance

• Annual clinical examinations of the chest/reconstructed breast are recommended after bilateral mastectomy, as a small risk of developing breast cancer remains. 4, 5, 6
• Mammograms are not recommended after bilateral mastectomy. 4, 5, 6
• Women with BRCA1/2 mutations should be monitored according to genetic/familial high-risk assessment guidelines and should consider risk-reducing salpingo-oophorectomy. 1, 4, 5, 6