Objective: Primary fallopian tube carcinoma represents a rare entity, accounting for about 0.75%-1.2% of all gynecological malignancies. The rationale of our study is to describe the prognosis of primary fallopian tube carcinoma. Methods: We retrospectively identified patients with FIGO stage I-IV, all histology types and grading primary fallopian tube carcinoma treated in three major oncological centers between January 2000 and March 2020. Exclusion criteria were bulky tubo-ovarian carcinomas, isolated serous tubal intraepithelial carcinoma or neoadjuvant chemotherapy. Results: A total of 61 patients were included. The vast majority of primary fallopian tube carcinomas were serous (96.7%) and poorly differentiated (96.7%) and arose from the fimbriated end of the tube (88.5%). Larger tumor size correlated with higher probability of correct preoperative differential diagnosis of primary fallopian tube carcinoma (p=0.003). Up to 82.4% of patients with small tumors (≤15 mm) presented with high FIGO stage (≥IIA). The most common site of metastasis was pelvic peritoneum (18.8%) and among 59% of patients who underwent lymphadenectomy smaller tumors had higher rate of nodal metastasis (42.9%≤10 mm vs 27.3%>50 mm). After 46.0 months of mean follow-up there were 27 recurrences (48.2%). The most common site of relapse was diffuse peritoneal spread (18.5%). The 5-year disease-free survival was 45.2% and 5-year overall survival was 75.5%. Of note, 42.9% of patients with stage IVB survived >36 months. Conclusion: Primary fallopian tube carcinoma is a biologically distinct tumor from primary epithelial ovarian carcinoma and it is mostly located in the fimbriated end of the tube. In addition, it is characterized by a high rate of retroperitoneal dissemination even at apparently an early stage and its size does not correlate with FIGO stage at presentation.
