Influence of age and gender on surveillance for colorectal tumors in low-risk asymptomatic population

Background: We tried to find the possible "downstream" approach for the low-risk asymptomatic population surveillance for colorectal tumors by fecal occult blood test (FOBT) and flexible sigmoidoscopy (FS) with the factors of age and gender. Patients and Methods: Retrospectively, 2187 asymptomatic low-risk cases received complete FOBT and FS. These cases also received complete colonoscopy(CF) for definite diagnosis and were separated into two groups by age (age≤49 vs. age≥50 groups) and gender (male and female groups). Results: The sensitivity and specificity to FOBT and FS were 44% and 98%, and 65% and 100% respectively for all cases. Significant positive FOBT, FS and CF results were noted in the age≥50 group (p=0.002, <0.001, <0.001, respectively). Positive FS and CF results were significantly noted in the male group (p=0.012, 0.009, respectively). After combination of age and gender factors, a positive FOBT result was significant in female cases with age≥50 years. (p=0.006). Positive FS and CF results were significant in male cases with age≥50 (both p<0.001). Conclusion: In the surveillance of a low-risk asymptomatic population for colorectal tumor, repeated FOBT might be considered in people of age≤49 years regardless of gender. In female and age≥50 years, FOBT might be considered first and then FS could be performed in positive FOBT cases. In male and age≥50 cases, FS was considered first without FOBT for the surveillance.