Fecal immunochemical testing with a low hemoglobin threshold for colonoscopy resembled one-time, primary colonoscopy for detecting advanced neoplasias in the first-degree relatives of colorectal cancer patients, investigators reported in the November issue of Gastroenterology.
Annual fecal immunochemical testing (FIT), followed by colonoscopy if hemoglobin levels met or exceeded 10 mcg per gram of feces, detected all cases of colorectal cancer (CRC) and 61% of advanced adenomas in the study population, said Dr. Enrique Quintero and Dr. Maria Carrillo at the Universidad de la Laguna in Spain and their associates.
But one-time colonoscopy was better than FIT for detecting all neoplasms as a whole in first-degree relatives of patients with CRC, the researchers reported. Based on the findings, initial screening with FIT should be considered when access to colonoscopy is limited, especially if patients are more likely to accept FIT than colonoscopy, the investigators said (Gastroenterology [doi: 10.1053/j.gastro.2014.08.004]).
Courtesy: American Gastroenterological Association
The trial included 1,918 first-degree relatives of patients with CRC. In all, 782 relatives were randomized to one-time colonoscopy, while 784 were assigned to annual FIT for 3 years, the researchers reported. Advanced neoplasia was detected in 3.9% of the FIT group and in 5.8% of the primary colonoscopy group, the investigators said (odds ratio, 1.56; 95% confidence interval, 0.95-2.56; P = .08). Rates of detection of advanced neoplasia also were similar between the FIT and primary colonoscopy groups when participants were stratified by age, sex, age of family member with CRC, type of familial relationship, and number of relatives with CRC, the researchers reported. However, primary colonoscopy identified significantly more nonadvanced adenomas (19.8%) than did FIT (5.4%), they added (OR, 4.71; 95% CI, 3.22-6.89; P less than .001).
Participants with negative FIT results were invited to undergo colonoscopy at the end of the study, the researchers said. Follow-up colonoscopies in these relatives showed that FIT had missed 39% of advanced adenomas but no cases of CRC, they reported. To detect one case of advanced CRC, only 4 relatives in the FIT group needed to undergo colonoscopy, compared with 18 members in the primary colonoscopy group, they added. “A potential benefit of FIT over primary colonoscopy in familial CRC screening is that it may save a substantial number of unnecessary colonoscopies, thus preventing harm and lowering costs,” the investigators concluded.