The book mentioned by the OP discusses the "virus theory" of cancer, which was very popular for a while.

What people eventually realized was that cancer is the result of genetic mutations and there are many potential causes of the mutations, viruses being one of them. E.g. HPV can lead to cervical, anal, throat cancer, etc.

An interesting book. The books feels a little bit narrowly focused on medical oncology, but the author is a medical oncologist, so you'd expect that.