Cancer is a name given to a collection of hundreds of different diseases that all have the common feature of being cells that lost the control to stop dividing. The reason cancer is such a bitch to control is because they’re human—they are your cells. Most other treatments for viruses, bacteria etc all rely on disrupting some feature of their life cycle that doesn’t coincide with our own cells. But with cancer it’s much harder to do that because almost every attack against them will hit healthy cells, too. That’s why you see chemotherapy being so hard on people, because it’s poisoning them along with the cancer.
All that said that’s pretty much why cancer is so hard to treat, and why there’s not really a “cure” for cancer short of thanos snapping all of the cancer cells out of existence
Oh my bad sorry to overexplain then! I just figured I might as well write it all out just in case