A population-based audit of the clinical use of faecal occult blood testing in primary care for colorectal cancer.

AIM

Symptoms related to colorectal cancer (CRC) are common. We investigated the value of the faecal occult blood test (FOBT), when administered in primary care, in the diagnosis of CRC.

METHOD

All patients who underwent a FOBT (Hemoccult II) at 20 public primary care centres in Sörmland County, Sweden, during 2000-2005, were included (n=9048). Linkage to the Swedish Cancer Registry identified all cases of CRC. Symptoms recorded at the time of the FOBT were retrieved from the patient records. The outcome from the FOBT to diagnosis and subsequent survival was compared between patients who were FOBT negative and patients who were FOBT positive.

RESULTS

One-hundred and sixty-one patients were diagnosed with CRC within 2 years after undergoing a FOBT in primary care. These comprised 18% of all 917 patients diagnosed with CRC in the county during the study period. In 41 (25.4%) of the 161 patients the test was negative. Symptoms related to CRC were documented for 158 (98%) patients at the time the FOBT was administered. The median investigation time from the FOBT test to the diagnosis of CRC was 91 days: 80 days for FOBT-positive patients and 188 days for FOBT-negative patients (P<0.001). This difference was significant independent of age, sex and site of tumour. The hazard ratio for FOBT negativity, 3 years after the FOBT, when adjusted for age and sex, was 1.47 (95% CI, 0.81-2.68).

CONCLUSION

Despite having suggestive symptoms, 41 (4.5%) of 917 CRC patients had a negative FOBT result in primary care. This was associated with diagnostic delay and, potentially, a worse outcome.