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. Author manuscript; available in PMC: 2013 Jun 1.
Published in final edited form as: Gut. 2012 Apr 5;61(6):794–797. doi: 10.1136/gutjnl-2012-302014

Figure 1.

Figure 1

Illustration of the disparity between the continuum model and the two-colon concept. The frequencies of molecular features such as CIMP-high, MSI-high, and BRAF mutation increase linearly from the rectum to the ascending colon according to the continuum model, and as supported by our recent data (left).[15] Previous studies have typically lumped together all distal tumours, and all proximal tumours, and compared the frequencies of various molecular features. Data from numerous previous two-colon studies appear to support the two-colon concept (right, top), even where the likelihood is that a continuum exists for the measured marker along proximal-distal axis of the bowel (right, bottom). The design of two-colon studies does not permit adequate evaluation of the linearity of marker frequency by colon subsite.