Answer:
Cancer and hemorrhoids are completely two different terms. If proper care and treatment is not taken and hemorrhoids get worse then it can turn into gangrene.
Both colorectal and anal cancer have symptoms which may cause them to be mistaken for far more benign diseases, like hemorrhoids.
The biggest difference between the symptoms of hemorrhoids and those of colorectal cancer is that rectal bleeding from colorectal cancer will most likely be dark and/or already hardening while hemorrhoidal bleeding is usually bright red and very fresh.
If you want to know more about the relation between Cancer and Hemorrhoids, you can read: