Clinical Question

Are the uptake and detection rates better for the fecal immunochemical test (FIT) than for older guaiac-based screening tests for colorectal cancer?

Bottom Line

FIT is more sensitive and specific than the older guaiac-based fecal occult blood tests (gFOBTs) when screening for colorectal cancer. We now know that it is also more acceptable to patients and increases uptake in a centrally administered screening program. Physicians should offer patients the option of FIT or colonoscopy, and should replace their stocks of gFOBTs with FITs in their office practice. (Level of Evidence = 1b)

Synopsis

Previous randomized trials have shown that screening for colorectal cancer, even using the older gFOBTs, reduces disease-specific mortality. The most recent modeling estimates put this benefit at 220 to 270 life-years saved per 1,000 persons screened over their lifetime (https://www.uspreventiveservicestaskforce.org/Page/Document/UpdateSummaryFinal/colorectal-cancer-screening2). The FIT is a newer test for occult blood in the stool that is specific to human blood, and only requires a single sample with no food restrictions prior to testing. But do these advantages translate into greater uptake by patients? In England, the standard of care has been to mail three gFOBT cards to all persons 60 to 74 years of age every two years, and ask them to obtain two samples from each of three separate bowel movements. The current study gave every 28th person (in a region with 1.2 million screening candidates) the newer FIT; the other 27 persons got the standard gFOBT. Although not randomized, the authors assure us that the order of persons on the screening list is not influenced by age, sex, socioeconomic status, or other demographic factors.

They found that the uptake was significantly higher for the FIT than for gFOBTs (66.4% vs. 59.3%; P < .001). Uptake increased for men and women in all age groups and in all levels of socioeconomic status. The increase in uptake was somewhat greater in men than in women. And among previous nonresponders, the response rate approximately doubled. At lower cutoffs for hemoglobin, the number of colonos-copies required increased three- to fourfold, but the detection rate for cancers and advanced adenomas was also significantly higher. For example, using a cutoff of 40 mcg per g of feces, 5.2% of persons had a positive FIT result compared with 1.7% using gFOBTs; the rates of cancer and advanced adenoma detection were 0.24% and 1.29% with the FIT, and only 0.12% and 0.35% with gFOBTs.

Study design: Nonrandomized controlled trial

Funding source: Government

Allocation: Concealed

Setting: Population-based

Reference:MossSMathewsCDayTJet alIncreased uptake and improved outcomes of bowel cancer screening with a faecal immunochemical test: results from a pilot study within the national screening programme in England. Gut2017;66(9):1631–1644.