Digital rectal examination in primary care not that accurate?

Albrecht Durer Hand (21 May 1471)

http://astrodreamer.squarespace.com/blog/2008/6/19/miles-davis-irving-penn-durer-emerson.html

I found this a bit surprising:

1069 patients were referred to the University Hospital of North Staffordshire to the 14-day urgent colorectal cancer referral service. Of these, 108 patients were referred as having a 'palpable rectal tumour'. Only 32 of the 108 were found to have a rectal lesion on examination in the hospital. Ten tumours were missed by GPs' DREs.

The diagnostic value of digital rectal examination in primary care for palpable rectal tumour
C. W. Ang, R. Dawson, C. Hall and M. Farmer Colorectal Disease
Published Online: 14 Sep 2007
DOI 10.1111/j.1463-1318.2007.01381

http://www3.interscience.wiley.com/journal/120125657/abstract