Bilateral Breast Cancer

Synchronous and metachronous bilateral breast cancers:
- Appear in 1% to 20% of patients with breast cancer
Improvements in screening and the increased use of MRI:
- Often diagnose more early-stage synchronous bilateral cancer
The role of MRI in the preoperative planning:
- Is controversial and may be partly responsible for increasing mastectomy rates in the United States
MRI may identify additional lesions in both the ipsilateral and contralateral breast in many women diagnosed with unifocal breast cancer:
- Many of these additional lesions are often found to be benign once additional diagnostic imaging is performed and biopsies are completed
- Additional MRI findings should not prompt surgeons to recommend mastectomy:
  - Unless they are biopsy-proven to represent additional sites of malignancy not amenable to breast conservation, and/or the patient was inclined toward mastectomy prior to MRI findings
Retrospective studies evaluating the outcomes of synchronous bilateral breast cancer:
- Are limited by small cohort sizes, differing definitions, and non-matched unilateral patients as controls
- Most retrospective studies show no differences in local recurrence or survival for bilateral breast cancers:
  - Making bilateral breast-conserving treatment a safe option for early-stage synchronous cancers
References
- Heron DE, Komarnicky LT, Hyslop T, Schwartz GF, Mansfield CM. Bilateral breast carcinoma: risk factors and outcomes for patients with synchronous and metachronous disease. Cancer. 2000;88(12):2739-2750.
- Intra M, Rotmensz N, Viale G, et al. Clinicopathologic characteristics of 143 patients with synchronous bilateral invasive breast carcinomas treated in a single institution. Cancer. 2004;101(5):905-912.