Yeah it's been going on for a while, and frankly I'm assuming there's probably dozens of things that have been approved for human consumption that simply shouldn't have been.

Be it drugs, food additives, packaging materials or disinfectants, it's clear that regulators are all too happy to be lobbied or pressured into squinting hard enough that a "small risk for negligible benefit" suddenly looks like "safe and effective". Do that repeatedly and the health effects can stack up. It's not death by the thousand cuts, it's death by the thousand carcinogenic coin flips.

Being fat (30 BMI) at the time of the linked study was 1.4 risk for colorectal cancer.

That looks like it should only account for +2.5% out of the increase (+12.8% for all cancer is the only number article gives), but a fairly big chunk anyway.

But most interesting is that those with insurance had 3.09 times the risk of the uninsured. So sounds like young people are getting more tests, they're finding polyps and early cancers, and getting treated early. That sounds like a good thing to me, not a scary story.

If you still think it's a terrible rise in cancer... being >50 was 11 times the risk. So enjoy your youthful worries while you can.

Does it predate the flu shot? That other shot that doesn't prevent what it's supposed to but that millions of people take every year anyway?

You're right though, it could be anything, or lots of things.

Thank you for the context. It looks like the article got cut off at the bottom of the page, sadly.

A study in BMJ Oncology last year reported a sharp global rise in cancers in people under 50, with the highest rates in North America, Australia and Western Europe.
Doctors are racing to figure out what is making them sick, and how to identify young people who are at high risk. They suspect that changes in the way we live—less physical activity, more ultra-processed foods, new toxins—have raised the risk for younger generations.
...
The risk of developing some cancers at a young age has increased for each generation born since the 1950s, studies suggest. One found that people born in the 1990s are at double the risk for early-onset colon cancer and four times the risk for rectal cancer, compared with people born around 1950.

These excerpts may suggest some kind of lifestyle or environmental (as in immediate surroundings) cause among first world countries. Finding a singular factor to explain everything seems unlikely.

Probably all the highly processed industrial sludge, I mean "heart healthy seed/vegetable oils" that are in nearly everything, the microplastics that are in literally everything and the massive amount of sugar people eat.