A study published in the British Journal of General Practice (BJGP) has found that FC testing has a high negative prediction value for colorectal cancer, which could be used to rule out the disease in patients with non-specific symptoms.
Gastrointestinal disorders make up around 8% of all GP consultations, but the average GP will encounter just one case of colorectal cancer a year.
Because symptoms are non-specific many patients are referred through the two-week wait referral pathway needlessly, with only 8% of referrals resulting in a positive diagnosis.
GP cancer referrals
This puts strain on services, the researchers said. Using FC to rule out cancer in patients where it is not high enough could be a better use of resources, they added.
GPonline reported earlier this year that one in three GPs say urgent referrals they have made for cancer scans have been blocked because of soaring pressure on diagnostic services.
The study looked at 654 patients at York hospital who had been referred urgently for suspected colorectal cancer through the two-week wait pathway from primary care.
They provided stool samples for the blinded determination of FC before any investigations were undertaken.
Among the patients, 39 had colorectal cancer and two had upper gastrointestinal cancers. All of the patients with colorectal cancer had a raised FC, suggesting the test could be used to rule out cancer in patients who return normal levels.
The researchers said: ‘FC offers the promise of a risk stratification for all patients with lower gastrointestinal symptoms, rather than the current focus on those with suspected colorectal cancer that distorts clinical thinking and becomes increasingly inefficient as the symptom based predictive value falls ever lower.
‘Large-scale, primary care based studies are required here. Whether FIT [faecal immunochemical occult blood testing] and FC have a synergistic or competing role is not clear. In the meantime, FC may be considered in place of FOB testing to support NICE guidance NG12 in areas where the FIT is not currently available.’