Although it is clear that the distribution of neoplasms has shifted more promimally over the last 20 years, the fact that the proximal colon is not included in this screening examination is considered an acceptable liability since the proximal colon continues to account for a minority of the cancers, approximatley 40%.

In addition, an even smaller proportion of colon malignancies (between 25% and 30%) occur as isolated proximal lesions without concomitant adenomas or cancers more distally (within the reach of the sigmoidoscope).

Copyright 2000