Effectiveness of a colonoscopic screening programme in first-degree relatives of patients with colorectal cancer

The study aimed to assess the diagnostic yield of a colonoscopy screening programme in first-degree relatives of colorectal cancer (CRC) patients and to identify factors associated with advanced neoplasia.

We conducted a cross-sectional study. Individual characteristics, family trees and colonoscopy findings of asymptomatic first-degree relatives of CRC patients were collected. The findings were classified into cancer (invasive carcinoma and/or non-invasive high-grade neoplasia), high-risk adenomas (≥ 10 mm and/or a villous component) and low-risk adenomas (tubular < 10 mm). The dependent variable was the presence of advanced neoplasia, defined as cancer and/or high-risk adenoma.

Two hundred and sixty-three relatives (147 females), 50.0 ± 11.5 (range, 25-75) years of age, agreed to participate out of a total of 618 who were invited (acceptance rate 42.5%). Index cases were diagnosed at 63.8 ± 12.4 (range, 37-88) years of age. The closest familial relationship was parent/offspring in 168 (63.9%) participants and sibling in 95 (36.1%) participants; 14.8% had three or more relatives with CRC/cancer associated with Lynch syndrome, and two or more affected generations were identified in 24.0%. Advanced neoplasia was found in 56 (21.3%) participants. Of these, invasive cancer, non-invasive high-grade neoplasia and high-risk adenomas were detected in five (1.9%), six (2.3%) and 45 (17.1%) participants, respectively. Low-risk adenomas were detected in 20 (7.6%) participants. Male sex (odds ratio, 2.59; P = 0.003) and sibling relationship (odds ratio, 2.74; P = 0.001) were independently associated with advanced neoplasia.

We detected advanced neoplasia in a considerable number of participants. Our data support colonoscopy screening in first-degree relatives of patients with CRC at an earlier age than in the medium-risk population. Male sex and sibling relationship were predictors of advanced neoplasia.