A total of 12 CRC cases were found in the screened group (0.6 percent of the screened persons), including one which was found during follow-up 60 months after the initial screening (0.05 percent of screened persons). In the non-screened group, there were 213 cases of CRC (1.0 percent). None of the non-screened patients, of whom five presented with synchronous cancers, and none of the persons who had been excluded from screening, had previously undergone a colonoscopy.
A total of 72 percent of the screened-group cancers (66.7 percent including the one detected during follow-up) and 19.7 percent of the cancers in the control group were at Tumor (T) stage one or two. One of the 12 persons of the screened individuals with a colorectal cancer and 51 of the 213 persons of the non-screened individuals with a colorectal cancer died because of their cancers. Colorectal cancer-associated mortality was clearly lower in the screened group.
The risk profile in the screened group was comparable to that in the general population. Risk factors such as lifestyle, smoking, and body mass index, as well as family history, were similar in both groups. “Blue-collar workers" had a higher incidence of CRC compared with “white-collar workers." The risk factors identified for CRC were a positive family history and smoking. The researchers noted that possible limitations of the study included the relatively low number of participants, confounding factors related to the ethnicity of the subjects, and that it was a non-randomized study.
The researchers found in this closed cohort study a substantial reduction in the incidence of colorectal cancer and colorectal cancer–related mortality in a sample of asymptomatic individuals undergoing a single colonoscopy screening compared with non-screened individuals.