by ecancer reporter Janet Fricker

Results from the first million people to be screened in the English Bowel Cancer Screening Programme (BCSP) show the initiative to be “on track” to match the 16% reduction in colorectal cancer (CRC) mortality found in recent randomized trials. The analysis, published in Gut, found that the proportion of left-sided cancers detected by fecal occult blood tests was higher than right-sided cancers.

In the study Richard Logan, from the University of Nottingham Medical School, and colleagues, reviewed data from one million people who had undergone screening in England between 2006 and 2009. The screening programme involved three fecal occult screening tests every two years for patients aged between 60 and 69 years.

Of the 2.1 million people invited to participate in the fecal occult screening programme, tests were returned by 49.6% of men and 54.4 % of women. An abnormal result was obtained in 2.5 % of men and 1.5 % of women, or abound 21,000 people altogether. Of the 17,518 participants undergoing further investigations (usually colonoscopy) 11.6% of men and 7.8% of women were found to have cancer, and 43% of men and 29% of women to have high risk adenomas. 

Altogether 77% of the cancers detected were left sided compared to 14% that were right sided. “Perhaps the most unexpected finding was the proportion of left-sided cancers which at 77% is substantially higher than the 66% found in non-screen detected CRC,” write the authors.

The results raise the possibility that the biology of right sided CRC may be more aggressive and hence less amenable to detection by screening tests, suggest the authors, or that right-sided cancers tend to produce detectable occult bleeding at a later stage than left-sided cancers.  Different screening strategies, they add, may therefore be required to effectively screen for right-sided CRC.

Reference.

R Logan, J Patnick, C Nickerson et al. Outcomes of the Bowel Cancer Screening Programme (BCSP) in England after the first 1 million tests. Gut. doi: 10.1136/gutjnl-2011-300843