10.22376/ijpbs.2019.10.1.p1-12 Volume 15 Issue 1 January - March Ovarian cancer is a challenging disease with a high mortality rate, emphasizing the need for effective diagnostic and prognostictools. Serum CA 125 levels have shown promise as a marker for ovarian cancer detection and monitoring. This retrospective study analyzesthe variations in CA 125 levels and their correlation with staging and histological subtypes in ovarian carcinoma patients. The study aims todetermine whether CA 125 levels correlate with ovarian cancer staging and histological subtypes. It is also an attempt to assess the changesin CA 125 levels before and after three cycles of neo-adjuvant chemotherapy and investigate the demographic characteristics of ovariancancer patients. This retrospective observational study analyses the case reports of 126 ovarian cancer patients diagnosed and treated at atertiary care cancer center in India. Patient demographic data, CA 125 levels before and after chemotherapy, histological types, and staginginformation were collected. Statistical analysis was performed using IBM SPSS. The analysis revealed that most patients were above 52 yearsold, married, and had children. Surface epithelial ovarian cancer was the most frequent histological type, with high-grade serous carcinomabeing the most common subtype. The majority of patients were diagnosed at advanced stages. CA 125 levels decreased after chemotherapy,but the difference was not statistically significant. Serum CA-125 levels hold value as a prognostic tool in ovarian cancer, aiding in diseasemonitoring and predicting progression. However, CA 125 levels alone may not be sufficient for determining treatment efficacy or prognosis.These findings contribute to our understanding of ovarian cancer and highlight the importance of monitoring CA 125 levels in assessingdisease prognosis and progression. Edakkadath Raghavan Sindhu,Aathira K. K.,Adarsh D,Maya Padmanabhan,Sangeetha K Nayanar Ovarian Cancer, CA125, Tumor marker, Histological subtypes, Surface epithelial ovarian cancer 80-87