Clinicopathologic characteristics and patient outcomes of malignant phyllodes tumors: A multi-institution experience.

Abstract

e23528 Background: Phyllodes tumors (PT) are rare fibroepithelial neoplasm that start in the connective tissue of the breast. PTs are classified by their histologic features into benign, borderline, and malignant. Malignant PTs account for about 1 in 4 PTs and are most likely to come back after treatment and metastasize. This study was conducted to investigate the incidence, clinical presentation, pathological characteristics, treatment and outcome of malignant PTs in the Abu Dhabi Health Services Company (SEHA) institutions in the United Arab Emirates. This will provide a better insight on factors that influences outcome in these patients. Methods: We retrospectively analyzed data of malignant PT treated at Tawam Hospital, Sheikh Khalifa Medical City and Sheikh Shakbout Medical City between 2000 and 2020. Information was obtained from the SEHA Cancer Registry and analyzed using excel software. Results: A total of 36 patients with malignant PT were identified. All were females. The median age at diagnosis was 38 (17-60). Median BMI at diagnosis was 27 (21-47). Out of the 36 patients, 3 were diagnosed during pregnancy, 16 (44%) had a history of fibroadenoma and 8 had a family history of first degree relative with breast cancer. Initial symptom at presentation was breast mass in 30 patients and fungating breast mass in 6 patients. Out of the 26 patients, 4 (11%) had tumor < 5 cm, 10 (28%) had tumor ≥5 cm and < 10 cm, 22 (61%) had tumor ≥10 cm, 2 patients had heterogenous tumor with component of invasive ductal carcinoma, no patient had metastatic ipsilateral axillary adenopathy at diagnosis and 5 (14%) presented with de-novo metastatic disease (4 in the lung and 1 in the contralateral breast as the first metastatic site). Of the 31 patients with non-metastatic disease at presentation, 17 underwent mastectomy, 14 underwent lumpectomy, 14 had axillary lymph node dissection, 8 had no axillary surgery, 9 had sentinel lymph node biopsy, 16 had adjuvant radiation therapy and 2 had adjuvant chemotherapy. Of the 31 patients, 13 patients developed locoregional recurrence of which 9 had positive margin on initial surgery and 4 had negative closet margin of ≤1 cm, 7 patients developed metastatic disease of which lung and/or the chest are the main sites. Of the total population to date, 7 patients passed away from the disease. Conclusions: Malignant PT patients are a unique population with limited characterization to date. Our study demonstrates the clinical and pathological characteristics and the treatment pattern of these patients. Further analysis is underway to assess risks associated with surgical and survival outcome of this disease.