What to do if I am 18, ive been told if u have thin stools, its sign of colon cancer. Should I worry.?

Should be checked. Thin stools can be a sign of rectal, not colon cancer. "Pencil" stools are caused by the cancer in the distal rectum or anus causing a severe narrowing which allows only a thin stool to pass. If the thin stools continue, you should see you're PCP and may need a colonoscopy.
Not accurate. This is not accurate. The stool became thin in the very advanced stage of colon cancer. Before the total obstruction of the colon. Usually you ll have many symptoms of colon cancer before the thin stool.