Histologic classification and prognosis factors in phyllodes tumors of breast

Abstract Objective: To study the relationship between morphological characteristics, grading, diagnosis and prognosis in phyllodes tumors (PT) of the breast. Methods: A retrospective study was carried out on 83 PTs diagnosed between 1999 and 2003 that were classified semi-quantitatively according to the WHO recommendation. Follow-up data was available for some cases, and Cox regression analysis was used to evaluate factors affecting metastasis and recurrence. Results: All cases were classified into the benign (57.8%), borderline (28.9%) and malignant (13.3%). The overall recurrence rate for the 72 cases with follow-up data was 20.8% (15/72), and was 17.5% (7/40) in benign, 22.7% (5/22) in borderline and 3/10 in malignant PT, respectively, with no significant difference (P>0.05). The median interval between the initial diagnosis and the first recurrence was 24 months. Lung or bone metastases occurred in 1/22 borderline and 3/10 malignant PT patients 5 years post-surgery. The mitotic count and the degree of stromal cell atypia were significantly correlated with recurrence (P=0.001 and P=0.006). Multivariate analysis showed that severe stromal cell atypia was an independent predictor of recurrence-free survival in PT [HR=6.40 (95% CI=1.378 to 29.732), P=0.018]. Conclusions: Each parameter in the histological grading of PT may have different prognostic value, and markedly increased mitotic count and were predictive of relapse.