Sensitivity of early colon cancer screening tests
BC Cancer and its Laboratory Services have identified an issue with the test used to screen for colon cancer. Recent fecal immunochemical test (FIT) results show an increase in the number of positive screens—more patients are testing positive than is typical. This higher rate was detected by the improved monitoring put in place last year.
A problem with the reagent used to test the fecal samples in the labs has been identified. A new reagent has been in use since mid-December 2017, when testing resumed after a 3-month suspension due to similar issues. The new reagent was performing to expected standards until very recently.
Testing will continue; however, physicians and patients are being informed that there will be a higher-than-normal percentage of patients who are referred for a follow-up colonoscopy. The provincial colon screening program recommends all patients with abnormal FIT results have a follow-up colonoscopy.
A positive FIT result is common and does not mean that the patient has cancer. On average, 15% of patients screen positive and require further testing. It is expected that an additional 5% of patients will now screen positive, whereas previously, they would have had a borderline negative result.
BC Cancer, Laboratory Services, and the Ministry of Health are exploring all options to address this situation.
Quick facts about colon cancer and screening:
- Screening can save lives by detecting noncancerous polyps and cancer early.
- Colon cancer is easier to treat when found at an early stage. When it’s detected at its earliest stage, survival rates are approximately 90%.
- FIT is a routine screening test recommended for people between the ages of 50 and 74 at average risk of colon cancer. It detects blood in the stool, which can be an early sign of colon cancer.
- Screening is only recommended for people who are not experiencing symptoms of colon cancer. Symptoms can include blood in the stool, abdominal pain, change in bowel habits, or unexplained weight loss. Anyone experiencing these symptoms should talk to their doctor about diagnostic testing they may need.
- Factors that put people at greater risk include having a first-degree relative (parent, sibling, or child) diagnosed under the age of 60, two or more first-degree relatives diagnosed at any age, and a personal history of adenomas.
For more information on the colon screening program, visit BC Cancer’s screening website at www.screeningbc.ca.