Pure mucinous carcinomas of the breast: prognostic study including DNA flow cytometry

Prognostic factors for pure mucinous carcinomas of the breast are controversial; data on DNA ploidy and S-phase fraction (SPF) are lacking. We examined the relation of these parameters with histological features and patient survival.

DNA flow cytometry was performed on 69 fresh or frozen pure mucinous carcinomas samples. Results were interpreted according to patient survival.

Tumor size exceeded 2 cm in 40.5% of cases. Lymph nodes were involved in 11.5% of cases and never when tumor size was less than 2 cm. Aneuploidy was only observed in one-quarter of the tumors. Very few tumors had a high-SPF or a high histological grade (7.2% of all cases). These two parameters were of prognostic value respectively for disease-free (P=0.035) and overall survival (0.050). Patients with tumors>2 cm had shorter overall survival than patients with tumors≤2 cm (P=0.028). Disease-free and overall survivals were not influenced by nodal status and hormone receptors (HRs) status. Patients with aneuploid tumors had shorter disease-free survival than patients with diploid tumors (P=0.031). The combination of tumor size and DNA ploidy was strongly predictive of survival (P<10(-3)): six patients with large aneuploid tumors had a poor outcome (1-year overall survival 16.7%).

We identified a subset of patients with a poor prognosis, namely those with large aneuploid tumors. This study confirms the good prognosis of pure mucinous carcinomas, particularly when tumor is less than 2 cm (corresponding to cases without lymph nodes involvement), thus challenging the need for axillary nodal examination.