During radiation for colon cancer, there was a wall thickening of the bladder, but the doctor told my husband that theres nothing to worry. what could?

Nothing to worry: There likely is nothing to worry about. If you are experiencing any symptoms, such as urinary frequency or urgency, i would recommend seeing a urologist.

More details: Acute symptoms from pelvic radiation therapy include bladder irritability and inflammation maybe that's what your physician was explaining to you.

Depends: Bladder thickening may be nothing but should probably be investigated further. A few details would help: what was the stage and location of the colon cancer? What kind of surgery did he have? If it was rectal cancer (most likely since he got radiation) did he also get chemotherapy and was it given with radiation, after surgery, before surgery or all? Does he have any urinary bleeding or burning?