If you have a fecal immunochemical test (FIT) and you test positive, you will need to undergo a follow-up colonoscopy. Based on the findings of a new study, don’t delay: The study, published in JAMA in 2017, found an association between waiting more than 10 months for a follow-up colonoscopy and increased risks for colorectal cancer and later-stage colorectal cancer at the time of diagnosis.
To evaluate the impact of timing between a positive FIT and colonoscopy, researchers evaluated data on more than 70,000 people whose FIT was positive. They found no significant difference in detecting any colorectal cancer or advanced-stage disease between people who had their follow-up colonoscopy within the subsequent eight to 30 days and those who underwent colonoscopy within nine months. But the risks for any colorectal cancer and advanced-stage disease were significantly higher for people who put off their colonoscopy for 10 months or more.
Though it is believed to take years for a colorectal polyp to grow into cancer, the findings of this study raise the possibility that polyps detectable by FIT might be on the road to cancer progression within six to 12 months after screening. Though further research is needed to determine whether the relationship between timing and cancer development is causal, for now it’s wise to play it safe. Book a follow-up colonoscopy within a reasonable window.