A tortuous colon is one that is longer than the usual colon and has one or more extra loops to it. It usually is not serious unless the bowel becomes twisted (volvulus). It does NOT lead to cancer or mean that one is pre-disposed to develop cancer. This condition may sometimes make having a colonoscopy difficult and in extreme cases may prevent the practitioner who is performing the colonoscopy from being able to examine the entire colon.
If you are having bowel symptoms always tell your physician and let her/him decide the next step.