Histological Risk Factors for Local Recurrence of Phyllodes Tumors of the Breast

Background/Aim: The rate of local recurrence (LR) of phyllodes tumor (PT) varies from 4 to 18%. Several histological risk factors of LR of PT are known. The aim of this study was to estimate the LR rate of PT according to PT grade and to evaluate histological risk factors of PT LR in our retrospective cohort. Patients and Methods: This was a two-center study, conducted from 1995 to 2019. All patients with PT diagnosed on surgical specimen were included. PT was diagnosed histologically according to the grade category defined by the 2012 World Health Organization classification as benign, borderline or malignant PT. Univariate analysis and then multivariate logistic regression analysis were performed to determine histological risk factors of LR of PT. Results: A total of 224 patients with PT were included: 152 with benign, 49 with borderline and 23 with malignant PT. The median and standard deviation for the duration of follow-up was 136.60 ± 167.43 months, and 18 patients (8.04%) developed LR: 7 (4.61%), 7 and (14.29%) and 4 (17.39%) with benign, borderline and malignant PT, respectively. In univariate analysis, LR was statistically increased for histological size ≥45 mm (p=0.003), borderline/malignant TP (p=0.006) and dense stromal cellularity (p<0.001). In multivariate analysis, only histological size ≥45 mm and cellularity were statistically associated with LR (odds ratio=1.83, 95% confidence interval=1.06-9.83, p=0.04; and odds ratio=3.69, 95% confidence interval=1.11-12.28, p=0.03, respectively). Conclusion: Histological size ≥45 mm and dense stromal cellularity were demonstrated as histological risk factors of LR of PT. In our cohort, no association was found between LR and PT grade nor LR and surgical margins ≥10 mm.