Primary and Secondary Breast Sarcoma: Clinical and Pathological Characteristics, Prognostic Factors, and Nomograms for Predicting Survival

Background: Breast sarcoma is one of the rare types of breast tumors with different features and outcomes compared to carcinoma. Our study aims to describe the clinical and pathological characteristics of primary breast sarcoma (PBS) and secondary breast sarcoma (SBS) along with determining prognostic factors and developing nomograms for predicting survival. Methods: Using the Surveillance, Epidemiology, and End Results (SEER) Program, female patients diagnosed with breast sarcoma between 1975 and 2016 were identified. Cox regression was used to evaluate the association between survival and clinical features. Results: Out of 1334 included patients, 816 had PBS and 518 had SBS. PBS had a significantly better overall survival than SBS with median survival months of 107 for PBS and 45 for SBS. The primary tumor site did not have a significant impact on the survival of SBS. Cox regression showed worse survival of PBS patients who were > 60 years (HR 3.04, 95% CI 2.46-3.74) and had tumor size > 50 mm (HR 2.01, 95% CI 1.61-2.51). Being not married was associated with worse survival of PBS (HR 1.29, 95% CI 1.06-1.56) and SBS (HR 1.50, 95% CI 1.19-1.90). Surgery was associated with better survival of PBS (HR 0.60, 95% CI 0.42-0.85) and SBS (HR 0.46, 95% CI 0.31-0.68). The C-indexes of created nomograms were 0.73 for PBS and 0.69 for SBS. Conclusion: Age and size were the most important prognostic factors for the survival. Surgery was associated with better survival. However, radiation and chemotherapy did not show significant improvement in survival.