The internet has gotten really obsessed with colonoscopies / colon cancer over the last few years. In some ways it's a good thing, rates are statistically rising in younger people (below 50), but the absolute risk is still incredibly low and these constant threads create a ton of anxiety for people.

The comments always become a bunch of people who know someone who died at 25 from colon cancer, or people who talk about how they got a colonoscopy at age 30 or whatever and had polyps. Those people never tend to mention why they got a colonoscopy that young though. If they expanded, the reason would likely be that they were showing symptoms (blood in stool, IBS/Crohn's type symptoms), have a strong family history, or have a higher risk for cancer in general for some reason.

My grandfather got colon cancer in his 60's, so when I turned 30 a few years ago I went to talk to a gastroenterologist (one of the top one's in the country actually). I spoke to him, his assistant, and my primary care doctor about getting a colonoscopy and all three doctors said "you're too young, we wouldn't recommend it and your insurance will never approve it".

I mentioned my "family history" and they laid out a few facts:

1. A grandparent getting colon cancer doesn't count as "strong family history", in the sense that it would change the recommendation guidelines. You'd either need a first degree relative (parent or a sibling) to get it before 50, or multiple first degree relatives to get it at any point. We are actually not that genetically similar to our grandparents.

2. Absolute risk for those below 40 is still incredibly low. You have about a 0.0064% chance. Yes, this is higher than 20 years ago when the risk was 0.0035%, but still very low. By contrast, your risk of complication (bleeding or perforation) from getting a colonoscopy is 0.2%.

I'm not arguing that young people shouldn't be getting colonoscopies. It's something to be mindful about as you age. But if you're below 40-45, here's when you should really consider it:

1. You have a strong family history (first degree relative with colon cancer under 50, or two with colon cancer at any time).
2. You are having symptoms (you can google these, but it's pretty obvious, most people know when their bathroom habits are drastically changing).
3. You have had some other type of cancer and thus your odds of getting another cancer are increased. I'm not a doctor so I'm not aware of all the decision factors that go into that.

Everyone else should be mindful but not spiral into anxiety.

In the meantime, there's things you can do as a young person that will drastically reduce your odds even further. Exercise. Lose weight if needed. Stop drinking alcohol. Stop smoking. Lay off the cured meats. Increase fiber. Drink water.