My dad, 79, has spots of blood on his depend (diaper), does anyone have any experience with this?

My DW gets them from pressure sores and scratching them. I am still working on clearing them up.

We had same problem with my grandma. She had uterine cancer we later learned.

You need to have him tested. It could be anything. Bladder cancer prostrate. A urine test will show it.

It certainly can be a symptom of bowel cancer. The doctor is the one with the experience he needs.