Actually, it's quite a bit like malaria. At one point it was insisted that it wasn't. Then they found the 1st infectious cause, and then the next and so on. The American Cancer Society now puts it at 15 to 20% infectious cause.
And that's not including the liver fluke they just found to be causing cancer in some Viet Nam veterans.
Having something cause cancer 40 or 50 years after the first infection makes it very hard to find that infectious cause. So I expect they are a long way from finding the last infectious cause for cancer.
Ok malaria was a bad choice!
The point I was trying to make was there will be no single cure for cancer. There are cancers from viral infections - e.g., HPVs, cancers caused by environmental conditions - radiation & chemical, cancers due to genetic
So lot of cancers to overcome and likely to come from modern environment & life style changes so a lot of work to be done!