Clinical outcomes and patterns of care in the treatment of carcinosarcoma of the breast

PURPOSE: Carcinosarcoma of the breast is a rare yet highly aggressive tumor accounting for <1% of all breast cancers, for which guidance on optimal management and prognosis are sparse. The purpose of this study was to investigate population‐based treatment patterns and overall survival (OS) outcomes in patients with this diagnosis. MATERIALS AND METHODS: We queried the National Cancer Database for patients diagnosed with carcinosarcoma of the breast. All patients included were treated with surgery in the form of mastectomy or lumpectomy, with or without chemotherapy and/or radiation therapy. Patients with metastatic disease were excluded. Kaplan‐Meier analysis was used to estimate OS. Univariate and multivariable Cox analyses were used to determine predictive factors of OS. RESULTS: A total of 329 patients from 2004 to 2012 were identified. Median age at diagnosis was 58 years (range, 24‐90). Patients had T1 (21%), T2 (44%), T3 (25%), or T4 disease (10%). Most patients were node‐negative at diagnosis (77%). Breast conservation surgery was utilized in 33% of patients. Chemotherapy was used in 66% of patients. Less than half (44%) of patients received radiation therapy to a median dose of 50.4 Gy (range 35‐56 Gy), with a median 10 Gy boost used in 76%. With a median follow‐up of 40.0 months, 3‐ and 5‐year OS for all patients was 74% and 60%, respectively. Kaplan‐Meier estimates revealed the 3‐yr OS was 80% in patients receiving chemotherapy vs 59% without chemotherapy (P < 0.001). The 3‐yr OS was 82% in patients receiving RT vs 66% without RT (P = 0.001). On multivariable analysis, OS was significantly influenced by Charlson‐Deyo comorbidity index, insurance status, clinical T stage, surgical margin status, and treatment group, with trimodality therapy (HR: 0.45, 95% CI: 0.27‐0.78; P = 0.004) and surgery plus CT (HR: 0.54, 95% CI: 0.33‐0.90; P = 0.02) being associated with the greatest OS. Logistic regression revealed only younger patients were more likely to receive trimodality therapy. CONCLUSIONS: Carcinosarcoma of the breast is associated with relatively poor rates of OS. The addition of CT and RT to surgery improves OS. Trimodality therapy and surgery plus CT were associated with the greatest OS compared to surgery alone.