Contralateral prophylactic mastectomy: Weighing the risks of delayed chemotherapy, radiotherapy, and hormonal therapy.

Background: Many patients with unilateral breast cancer opt for contralateral prophylactic mastectomy (CPM) at the time of therapeutic mastectomy (immediate CPM) or following completion of adjuvant therapy. Studies show that immediate CPM increases the risk of surgical complications related to unilateral mastectomy (UM) alone, which may lead to delays in adjuvant therapy initiation. However, it is unclear if these complications cause clinically significant delays in initiating adjuvant chemotherapy, radiotherapy, or hormonal therapy.

Methods: A retrospective chart review was conducted on patients with breast cancer who underwent immediate CPM versus UM alone at Columbia University Medical Center from January 2000 to December 2020. Patient demographic and oncologic characteristics; complications; and timing of adjuvant chemotherapy, radiotherapy, and/or hormonal therapy relative to therapeutic mastectomy were collected.

Results: In this study, 239 UM alone patients were propensity score matched to 239 immediate CPM patients. No significant difference in complication rates was found between the index and contralateral breasts in CPM patients. A similar percentage of CPM and UM patients experienced postoperative complications (19% vs. 17%, p = 0.64). No significant difference in time to adjuvant chemotherapy, radiotherapy, or hormonal therapy was found between CPM patients with complications and all CPM patients or all UM patients.

Conclusions: There is a lack of clear guidance for clinical decision-making regarding timing of CPM relative to adjuvant therapy. Our study suggests that immediate CPM does not significantly increase the risks of postoperative complications or complication-related delays in the initiation of adjuvant chemotherapy, radiotherapy, or hormonal therapy. This information may help patients and providers to plan, select, and schedule breast cancer treatment options.