Promoting quality in cancer screening

A large-scale study of more than 2.4 million people has shown that for every 1% increase in colonoscopy use, the risk of death from colon cancer dropped 3%. Led by Dr Linda Rabeneck from the University of Toronto, the research has highlighted the significant impact that increased colonoscopy has had on reducing mortality.1 While this research highlights the valuable contribution that colonoscopy has to offer in decreasng colorectal cancer deaths, variations in performance remain a concern. Dr Rabeneck et al recently discussed the incidence of postcolonoscopy colorectal cancer (PCCRC) in an article published in Frontline Gastroenterology – pointing out that incidence is around 5%, within three years of colonoscopy, in patients previously given “the all clear”.2 Outlining some of the limitations of colonoscopy, Dr Rabeneck and Dr Lawrence Paszat pointed out that, when consent is obtained, patients must be informed of the small risk that a cancer may not be detected.

The technique and experience of the practitioner are crucial factors, but the location of the cancer may also be important – evidence suggests that, in usual practice, colonoscopy may be less effective for lesions in the proximal colon. The question arises, is this due to the quality of the procedure or is biology an influential factor?2 Dr Rabeneck and Dr Paszat suggested that a possible explanation could be that proximal lesions may be associated with more rapid growth – while flat lesions (which are easier to miss during colonoscopy) may also be more common in the proximal colon. Gender, age and patient history are also factors affecting PCCRC and the authors pointed out that studies have shown that the risk is increased in:

• Women.
• Older patients.
• People with a history of diverticular disease or abdominal surgery.
• Patients with right-sided or tranverse colorectal cancer.