The recommended interval for colorectal cancer screening with flexible sigmoidoscopy (FS) was recently lengthened from 3 to 5 yr. Direct evidence supporting the longer interval is lacking. The appropriateness of the longer interval has been questioned.
Screening for colorectal cancer with flexible sigmoidoscopy: is a 5-yr interval appropriate? A comparison of the detection of neoplasia 3 yr versus 5 yr after a normal examination.