When physicians exam the rectum with a gloved finger, they are unlikely to find a real tumor and more likely to refer patients unnecessarily for further tests. Digital rectal exams are a poor way to accurately identify rectal cancer according to a recently published study from the United Kingdom.
Doctors reviewed all referrals made to the the urgent colorectal cancer system at University Hospital of North Staffordshire because of a palpable rectal tumor between May and December of 2006. Of 1,069 referrals to the system, 108 were for rectal tumors that general practitioners reported they felt during a digital rectal examination.
However after further testing, only 32 or those 108 exams actually was a rectal tumor.
And 10 tumors, potentially within reach of the examination, were missed by referring general practitioners.
Considering those referrals that actually were not tumors and the missed tumors, accuracy for digital rectal exam in finding very low rectal cancer was 29 percent.
The research team, led by C. W. Ang concluded,
Digital rectal examination in primary care for palpable rectal tumour has a sensitivity of 0.762, specificity of 0.917, positive predictive value of 0.296 and negative predictive value of 0.988. It is an inaccurate procedure and a poor predictor for palpable rectal tumour.
In the Guidelines for Screening and Surveillance for the Early Detection of Colorectal Cancer and Adenomatous Polyps published in the US in March, 2008, the panel warned,
Screening for colorectal cancer with guaiac-based FOBT in the office following digital rectal exam or as part of a pelvic examination is not recommended and should not be done.
SOURCE: Ang et al., Colorectal Disease, Volume 10, Number 8, October 2008.