This has a precondition: the existence of targets unique to the cancer cell. That's not necessarily true. In theory you can have cancerous cells that are (at least in the epitope-space) indistinguishable from normal cells. I'm not a doctor, and I guess (and hope) this is an usual case, but finding a truly unique and dissimilar mutation sounds pretty hard, training the immune system to detect it correctly without generalizing sounds even harder. Potential, sure, and I hope this proceeds and yields some therapies that are safer than chemotherapy, but we need to be realistic with what we'll probably get.

It's not that hard, in patients with cancer, it's very common for the immune system to go after the cancer specific mutations, until the cancer learns to express the cell-surface checkpoints that deactivate the immune system.

Its extremely rare (or at least I have not heard of it) to develop auto-immune activity during the course of cancer.

T-cell receptors that recogize HLA-bound epitopes tend to be extremely specific, and rarely go after other parts of the body. There's nothing special about cancer in this regard.

Making the immune system target tissue produced by the body, even a cancerous growth, is risky business.

The immune system does this all the time. They're called natural killer cells (NK Cells) and they regularly target cells that have become cancerous or infected.

Well yes, NK cells do that when we're infected with a malignant infection.

For the last hundred years, or so, vaccines have been non-malignant, so we've never had to question such things.

However, mRNA vaccines are an entirely novel class of technology, so it's appropriate for us question:

a) how long mRNA vaccines persist in the body? b) how discriminating are mRNA vaccines in which cells they impact? c) if any testing was done on the side effects of accidental intravenuous injection of mRNA vaccines? (given that there are plenty of blood vessels in muscle tissue) d) if any longitudinal studies have been done on mRNA vaccination of humans? e) if any comprehensive studies have been done on pregnant or nursing women injected with mRNA vaccines, and the impact on their infants?

Of course, but so are almost all cancer treatments, and many cancers are still a death sentence.

I've said above, if there aren't other treatment options available, it makes sense, but even then I don't know why one wouldn't use standard immunotherapies instead, which are less risky.

I think Moderna and Pfizer generated a lot of profit from the vaccines, and now they need a way of turning that over into capital, and they are still trying to find ways to have widespread adoption of regular mRNA treatments. But even millions or billions of dollars of capital investment will not yield a profit if its a bad investment.

Even if that statement were correct what difference does it make if you're going to be in the ground in six months?

The difference between those 6 months being a slow grind that gives you the chance to say goodbye to the world vs. sudden onset death from overwhelming immune malfunction. Quality of life is not an afterthought, even with the end in sight.

>the creation of foreign proteins

Those proteins are already there though, right?