Abstract Background Venous Thromboembolism (VTE) is an important cause of morbidity in cancer patients. Breast cancer patients undergoing surgical treatment are at an increased risk of VTE. The aim of this study was to determine the frequency of VTE in patients who underwent surgery for the treatment of breast cancer and to identify the related risk factors. Methods A historical cohort of patients at the São Paulo State Cancer Institute (ICESP) underwent surgery for breast cancer. The inclusion criteria covered patients with invasive breast cancer or ductal carcinoma in situ who had breast surgery anytime from January 2016 to December 2018. Results Of the 1672 patients included in the study, 15 had a confirmed diagnosis of VTE (0.9%), and 3 of these had deep vein thrombosis (0.2%), and 12, had pulmonary thromboembolism (0.7%). Clinical and tumoral characteristics did not differ between the groups. The incidence of VTE was higher in patients who had undergone skin-sparing mastectomy or nipple-sparing mastectomy (p = 0.032). Immediate reconstruction, particularly with abdominal-based flaps (4.7%), increased VTE events (p = 0.033). Median surgical time was higher in patients with VTE episodes (p = 0.027), and total hospital length of stay increased in days (6 days vs. 2 days, p = 0.001). Neoadjuvant chemotherapy and postoperative prophylaxis with Low Molecular Weight Heparin (LMWH) were associated with lower VTE rates (0.2% vs. 1.2%, p = 0.048 and 0.7% vs. 2.7%, p = 0.039; respectively) in these patients. Conclusions The incidence of VTE events in breast cancer patients who underwent surgery was 0.9%. Immediate reconstruction (especially with abdominal-based flaps), skin-sparing/nipple-sparing mastectomies, and longer surgeries were associated with increased risk. The LMWH postoperative prophylaxis reduced this risk. (VTE factors ICESP (ICESP 201 2018 167 1 0.9%, 09 0.9% , 0 9 (0.9%) 0.2%, 02 0.2% (0.2%) 12 0.7%. 07 . 7 (0.7%) groups skinsparing skin sparing nipplesparing nipple 0.032. 0032 0.032 032 0.032) abdominalbased abdominal based 4.7%, 47 4.7% 4 (4.7%) 0.033. 0033 0.033 033 0.033) 0.027, 0027 0.027 027 0.027) 6 ( vs 0.001. 0001 0.001 001 0.001) (LMWH (0.2 1.2% 0048 048 0.04 0.7 27 2.7% 0.039 0039 039 respectively especially flaps, flaps) skinsparing/nipplesparing skinsparingnipplesparing sparing/nipple mastectomies 20 16 0.9 (0.9% 0.2 (0.7% 003 0.03 03 4.7 (4.7% 002 0.02 000 0.00 00 (0. 1.2 004 04 0.0 0. 2.7 sparingnipple (0.9 (0.7 4. (4.7 (0 1. 2. (4. (4

OBJECTIVES: This study aimed to evaluate the clinical and imaging predictive factors for the diagnosis of phyllodes tumors in patients with inconclusive results from core needle biopsy (fibroepithelial lesions). METHODS: We retrospectively analyzed data of patients who underwent surgical excision of breast lesions previously diagnosed as fibroepithelial lesions. Numeric variables were analyzed using the Shapiro-Wilk and t-tests, and categorical variables were analyzed using the chi-square and Fisher’s exact tests. Multivariate logistic regression was performed to calculate odds ratios and detect predictive factors for the diagnosis of PT. RESULTS: A total of 89 biopsy samples were obtained from 77 patients, of which 43 were confirmed as fibroadenomas, 43 as phyllodes tumors, and 3 as other benign, non-fibroepithelial breast lesions. The mean tumor size was 3.61 cm (range, 0.8-10 cm) for phyllodes tumors and 2.4 cm (range, 0.8-7.9 cm) for fibroadenomas. The predictive factor for phyllodes tumor diagnosis was lesion size >3 cm (p<0.001). CONCLUSION: Our data indicate that fibroepithelial lesions of the breast larger than 3 cm are more likely to be phyllodes tumors.