Abstract:Objective To investigate the relationship between the expression of FASN, M2 tumor-associated macrophage（FASN）and the progression of ovarian cancer. Methods Based on data from The Cancer Genome Atlas（TCGA）and the Genotype-Tissue Expression（GTEx）databases, RNA-sequencing data of ovarian serous cystadenocarcinoma and corresponding normal tissues were extracted to evaluate the expression levels of FASN in pan-cancer and specifically in ovarian cancer. A retrospective inclusion of 60 subjects admitted to the Affiliated Drum Tower Hospital of Nanjing University Medical School from June 2018 to June 2023 was conducted. According to pathological results, they were divided into the normal ovary group（10 cases）, the benign ovarian tumor group（5 cases）, the ovarian cancer group （20 cases）, and the ovarian metastatic cancer group（25 cases）.Public database analysis was performed to explore the expression of FASN in pan-cancer, ovarian cancer and its correlation with prognosis of ovarian cancer. Immunohistochemical（IHC）staining was used to detect the protein expression levels of FASN, M0 macrophage marker — differentiation cluster（CD）68 and M2 macrophage marker — CD163. Correlation analysis and Kaplan-Meier survival analysis were conducted in combination with clinical data. Results Pan-cancer analysis of public databases showed that FASN expression was significantly elevated in various tumor tissues, including ovarian cancer, and FASN expression in tumor tissues was higher compared to normal tissues（P＜0.05）. Clinical case analysis showed that the high expression rate of FASN had an increasing trend in the order of normal ovary（10.0%）, benign ovarian tumor（20.0%）, ovarian cancer（80.0%）, and metastatic ovarian cancer（100.0%）. In 45 cases of ovarian cancer and ovarian metastatic cancer, patients with International Federation of Gynecology and Obstetrics（FIGO）stage Ⅲ-Ⅳ had significantly higher FASNIHC scores compared to stage Ⅰ-Ⅱ（5.76±1.44 vs 4.00±1.41, t=2.794, P=0.008）.The expression of CD68 increased with tumor progression（P＜0.05）, but was not significantly associated with the FIGO stage（P＞0.05）, while the CD163high-expression group had higher rates of lymph node metastasis, ascites, and FIGO stage（P＜0.05）. Univariate Cox regression analysis revealed that high expressions of FASN, CD68, and CD163 were risk factors for ovarian cancer recurrence（P＜0.05）. Kaplan-Meier survival analysis indicated that patients in the high-expression group of FASN, CD68, and CD163 had significantly shortened progression-free survival（P＜0.05）. Conclusion High expression of FASN can promote M2 polarization of TAMs in the tumor microenvironment of ovarian cancer, which is closely associated with a high risk of tumor metastatic and poor prognosis, and may be served as a potential biomarker for evaluating the biological behavior and prognosis of ovarian cancer.