Association of FOBT-assessed faecal Hb content with colonic lesions detected in the Florence screening programme

Abstract

We assessed the correlation between quantitative results of immunological faecal occult blood testing (I-FOBT) and colonic lesions (191 colorectal cancers, 890 adenomas) detected at colonoscopy in 2597 FOBT þ (cutoff 100 ng ml À1 Hb) subjects. At univariate analysis, a higher average faecal Hb content was significantly associated with male gender (P ¼ 0.003), age (P ¼ 0.02), and colonoscopy findings (P ¼ 0.000). Among adenomas, higher faecal Hb content was significantly associated with size (P ¼ 0.0000), presence of severe dysplasia (P ¼ 0.0001), presence of villous component (P ¼ 0.0002), and location in the left colon (P ¼ 0.003). At multivariate analysis adjusting for potential confounders, age (P ¼ 0.03), size (P ¼ 0.0000), and location in the left colon (P ¼ 0.0005) were confirmed as having an independent association with higher faecal Hb content. Immunological FOBT is confirmed to be a specific screening test to detect cancer and adenoma, with a low positivity rate (3.7%) and a high positive predictive value (41.5%). Faecal Hb content is significantly higher for those lesions (cancer and high-risk adenomas) screening is aimed at detecting. British Journal of Cancer (2007)

Comparison of a guaiac and an immunochemical faecal occult blood test for the detection of colonic lesions according to lesion type and location

“…As in other studies, in our population, the measured intensity of bleeding of invasive cancers was higher than that of high-risk adenomas (Levi et al, 2007;Ciatto et al, 2007). Moreover, we observed lower bleeding intensity in rectal cancers than in cancers in others locations, which is also in line with observations of Ciatto et al (2007) who found smaller although non-significant bleeding amounts for cancers of the rectum þ distal colon rather than proximal colon.…”

Test Performance of Immunologic Fecal Occult Blood Testing and Sigmoidoscopy Compared with Primary Colonoscopy Screening for Colorectal Advanced Adenomas

“…In addition, the impact of age, gender, and location of adenomas on performance of the most commonly used screening tests has not been extensively studied. Studies, applying colonoscopy only for FIT-positive individuals, have reported lower positivity rates and stool hemoglobin (Hb) in women, in younger age groups, and subjects with proximal lesions (7,11). As in these studies, colonoscopy data were not available from participants with a negative FIT, it remains unclear whether this discrepancy reflects a lower adenoma rate or possibly a lower sensitivity of FIT in these subgroups.…”

“…This negative result may be influenced by several factors contributing to a lower Hb concentration in stool. First, because of an increased degradation of Hb in case of a proximal lesion during colonic passage (11) and second because of the lower mean number and size of adenomas (37,38).…”

“…This lower Hb content in stool of female participants has also been reported by 2 other groups. The first study included only FIT-positive individuals and did not allow for the calculation of FIT sensitivity (11). The second study was a colonoscopy screening study by Brenner and colleagues (12).…”

Faecal haemoglobin concentrations vary with sex and age, but data are not transferable across geography for colorectal cancer screening

“…Moreover, Ciatto et al [7] have reported that f-Hb is significantly related to the presence of the very lesions, cancer and advanced adenoma, that screening is aimed at detecting. There is also considerable evidence that f-Hb increases as disease becomes more serious, from the normal to low-risk adenomatous polyps, then to higher-risk polyps and then to cancer, although there is much overlap between these groups [8,9].…”