Retroviruses can do something ordinary viruses cannot: insert themselves into human DNA.

Professor Angus Dalgleish, an oncologist who has spent decades studying viral links to cancer since his work on the earliest HIV research, explains.

Normal RNA viruses, even airborne ones, never touch your DNA. Retroviruses reverse that process, inserting themselves in and sitting there for a long time, which is exactly what the word "retro" refers to.

He points to the known cancer-linked viruses as the model for how this plays out: Epstein-Barr causing lymphoma, HPV linked to cervical cancer, hepatitis B and C both capable of causing cancer. In every case, it took years, sometimes decades, before the cancer ever emerged.

...It's happening a lot more quickly as of late.

@delbigtree