Doctors of that era, especially those who weren't too keen on hygiene, probably did not have exceptionally great life-spans.

I am a bit surprised that his own immune cells wouldn't stop it, but if cancer were easy for the immune system to deal with nobody would die of it.

Tasmanian devils apparently have little genetic diversity so they are more subject to this problem.

Why brag that you are uninformed?

Some of the more successful interventions for cancer are preventative (for example removing polyps during colonoscopies) and genetic counseling is common.

Makes me wonder: Is the cancer "industry" searching for causes or just after-the-fact treatment?

There are billions of dollars spent on this problem through huge DNA/RNA/Epigenomics/Chromatin Accessibility sequencing initiatives. There is also a huge amount of model system work such as mouse models.

Hmm, a disturbing and dangerous thought. But what does that mean for my comment? Who is paying me? What do they want? Will the lizard men of Hippocrates command the subtle ghasts of Papilla to inflict deep and lasting injury to our very souls?

Troubling. We must investigate.

The challenge though is mutations can happen in a plethora of ways and their effect is highly dependent on which gene is mutated. There is also the tissue context, e.g. inflammation, spatial structure, etc., that can setup a background for increased mutation. That is why targeted therapies are often the most effective, because they target the general causative feature of a given tumour subtype, the problem is not every protein can be targeted now and each tumour, even within the same subtype has their own unique mutational profile due to the stochasticity of the way mutations occur over repeated rounds of cell division.

And back to viruses, yes they cause cancer because they can mutate DNA. But it's pretty clear, most of the viral "enriched" cancer types are generally in places where transmission is commonplace, e.g. reproductive organs or head/neck.