Comparison of a guaiac based and an immunochemical faecal occult blood test in screening for colorectal cancer in a general average risk population.

Area of Science:

• Gastroenterology
• Oncology
• Medical Diagnostics

Background:

• The guaiac faecal occult blood test (G-FOBT) is a recommended colorectal cancer screening tool.
• However, its low sensitivity limits its global adoption and effectiveness.

Purpose of the Study:

• To compare the performance of G-FOBT with the immunochemical faecal occult blood test (I-FOBT).
• To evaluate I-FOBT at various positivity cut-off values for colorectal cancer screening.

Main Methods:

• A cohort of 10,673 average-risk patients underwent both G-FOBT and I-FOBT.
• Colonoscopy was recommended for patients with at least one positive test result.

Main Results:

• At a 20 ng/ml threshold, I-FOBT significantly increased sensitivity for cancer (50%) and high-risk adenomas (256%) but reduced specificity.
• A 50 ng/ml threshold for I-FOBT doubled advanced neoplasia detection without decreasing specificity.
• At 75 ng/ml, I-FOBT achieved 90% higher sensitivity and 33% fewer false positives for advanced neoplasia, with a similar positivity rate to G-FOBT.

Conclusions:

• Growing evidence supports replacing G-FOBT with I-FOBT for colorectal cancer screening.
• The benefits of I-FOBT are more pronounced for high-risk adenomas than for cancers.
• Automated reading technology enables selection of positivity rates for optimal sensitivity and specificity balance.