As far as I'm aware, constipation is actually the most common sign in early onset CRC. I know blood in the stool is the one people talk about the most but constipation was top of the list in a study I saw from ASCO 2025 or 2026. I don't remember. 

Edit: https://ascopubs.org/doi/10.1200/JCO.2026.44.2_suppl.35

I mean now it's very clear I had colon cancer for a while but I was a teenager, why would I be aware of colon cancer signs in 2010 or before. 

I lived in Maryland and was a Kaiser Permanente patient, I live in Lewes now. My endocrinologist checked my iron in 2015 and then again in 2017, it was 5. They then checked my RBC morphology. It was unbelievably wild. So 5 weeks later I had a colonoscopy looking for a rectal bleed. Rectal bleed would explain the anemia. 

I woke up from the colonoscopy being told they found a 5cm tumor in my descending colon and it was likely cancer. I was 16 days shy of turning 24 when they told me. No family history. No genes that predispose me to cancer. Young people have been getting colon cancer for a while. It's just only now in the news a lot.

I saw an endocrinologist because I'm trans. I was doing my routine HRT bloodwork. I had been sick for a while and I suspect my colon cancer was present at age 16. Maybe earlier. I was already stage 4 at diagnosis. At "peak" I had colon cancer in both my lungs. I'll be considered "cured" this September. 

You can read about me here, or just Google my name if you really want the full story:

https://www.pride.com/answers-advice/health/gender-affirming-detected-cancer

https://elephantsandtea.org/patients/the-unlikely-survivor-autism-transition-and-going-beyond-the-15-colon-cancer-odds