Paranoid about colon cancer. Great grandmother had it at 70. had runny + pencil stool last night. 24 y.o female. Should I get a colonoscopy screening?

Not likely. Unlikely that you have colon cancer as such a young age, but there's no harm n consulting a gastroenterologist, especially if the symptom persist.
NO. First see your doctor for examination and preliminary tests in office , if indicated will tell you. Just one relative having colon cancer is not enough to implicate genetics At 24 need to have a definitive indication (s) for colonoscopy . .
Maybe. A single pencil stool means nothing. If you're not better in a few days, get with your physician for a rectal exam. The stool caliber changes that cancer causes develop over weeks. However, your anxiety is understandable, and you may be a candidate for early screening. Best wishes.
Familial colon cance. While it's good to be concerned about your health, we don't want you to become paranoid! With regards to colon cancer, average risk doesn't increase until 50+ at which point we recommend some form of screening. Familial colon cancer is a consideration if parents or siblings have similar diagnosis. But one great grandparent doesn't qualify & certainly not if dx'd at 70yo. See http://goo.gl/F1kKqL.

Related Questions

Might it be that a colonoscopy prevents colon cancer, or is it simply a screening tool?

Yes it can. Colonoscopy is done to look for polyp which are precursors of cancer. So if the polyp is removed before it becomes cancerous, then we have prevented development of colon cancer. Read more...

Having rectangle stool. Had clean colonoscopy 20 months ago with good prep. What are the chances colon cancer would be causing this?

Low Chance ; BUT. At 40, a colonoscopy which shows no cancer less than 2 years ago is reassuring. Regardless, ASK your doctors advice about these new symptoms. Anorectal diseases such as hemorrhoids and fissures can cause changes to bowel caliber, but a thorough evaluation of the area needs to be done. While colon cancers are uncommon to grow in such a short span, it is not impossible. In short, see your doctor!! Read more...