PTGS2 and malignant colon neoplasm: Furthermore, the recent study has shown higher values of expression in colon cancer (93%) than in rectal cancer (87%), associating this decrease of Cox-2 expression to decreased disease-specific survival and decreased disease-free survival in rectal cancer but not in colon cancer, suggesting the Cox-2 expression as a predictive clinical biomarker of rectal but not colon cancer [37].