Breast sarcomas and malignant phyllodes tumours: comparison of clinicopathological features, treatment strategies, prognostic factors and outcomes.

We aimed to compare the clinicopathological features, treatment strategies and clinical outcomes of breast sarcomas (BS) and malignant phyllodes tumours (MPT), and determine their prognostic factors. Cases of BS and MPT diagnosed at the Department of Pathology, Singapore General Hospital from January 1991 to December 2014 were derived from department files. Clinicopathological features, treatment strategies and survivals of patients with BS and MPT were compared. Prognostic indicators for BS and MPT were identified. BS and MPT were comparable in all except one of their clinicopathological features. A significantly higher proportion of BS patients had a history of previous breast carcinoma and thus radiation to the chest as compared to the MPT group (17.6 vs 0 %, P = 0.018). There was no significant difference in survival outcomes between BS and MPT. The 5-year disease-free survivals (DFS) for BS and MPT were 59.1 and 57.4 % respectively (P = 0.816), while the 5-year overall survivals (OS) for BS and MPT were 86.5 and 78.5 % respectively (P = 0.792). Combining both groups of tumours, univariate analysis showed that DFS was significantly affected by multifocality (P = 0.019), histological subtype (P = 0.014), presence of malignant heterologous elements (P < 0.001) and margin status (P = 0.023). Margin status was the only parameter which had a significant impact on OS (P = 0.040). Multivariate analysis confirmed the above findings. BS and MPT are rare entities with remarkable heterogeneity. They share similar clinicopathological features and outcomes, provoking thoughts on their biological relationship and clinical significance of pathologic distinction.