229GENDER-SPECIFIC ER ISOFORM EXPRESSION IN COLORECTAL CANCER: IMPLICATIONS FOR PROGNOSIS AND MICROSATELLITE STATUSIn the study, ER-1 (wild-type) and ER-2 and ER-5 splice variants were analyzed for gender-specific differences in colorectal cancer. Using 91 primary colorectal carcinoma cases and 20 colorectal carcinoma cell lines, researchers explored the relationship between mRNA and protein expressions of ER?1 and ER?2. Results revealed an indirect relationship between ER?1 and ER?2 expressions in colorectal cancers, with 22% and 49% of cases showing differing behaviors. Low ER?1 expression correlated with poor differentiation and higher pT stage, while metastases were more common on the right side. Additionally, ER?1 expression positively correlated with trefoil factor protein expression. However, no correlation was found between ER? expression and tumor proliferation or response to 5-fluorouracil. The findings suggest that ER1 and/or ER2 isoform expression may influence the prognosis of colorectal cancers, potentially explaining gender-related differences in microsatellite status and disease outcomes. The opposing associations of ER1 and/or ER2 with colorectal cancer highlight the distinct activities of these isoformsKumar@gmail.comResearch1122021Colorectal carcinoma, ER? isoforms, Gender differences, Prognosis, Microsatellite instabilityDr. Anuj Kumar Pathakssistant Professor, Department of Pharmacology, Gouri Devi Institute of Medical Sciences & Hospital, Durgapur -713212, West Bengal, India