This is my first question on this Stack Exchange; I hope that I am following your posting guidelines correctly.

I am not someone who writes books (or is writing a book), but I do like to write short stories for my own entertainment. Most of my education is in computer science, cellular biology, and medicine.

When I was in undergrad, I learned (to my surprise) that cancer risk approached 100% as length of life extended. To put it another way, if you live long enough you'll die of cancer. Also, the reason for cells to become senescent is heavily linked to the shortening of telomeres. This made me think about a cure for cellular aging that involved a protein drug able to extend telomeres, at the cost of highly mutagenic properties. 

So, now to the question: **What would be the societal implications of cheap immortality that came with a vastly increased risk of cancer?**

In this situation, there would be no "maximum" life span, just a statistical one - how long on average a person lives before they express a malignant and untreatable form of cancer. Let's also say that most people die very quickly (~1 month) after cancer expression.

I would guess that most people would opt for the treatment, as in this scenario we will assume that the statistical life span is longer than what people would normally expect.

My guess is that it would lead to much more reckless/short-term-focused behavior, as even though median life span would be increased you would never know when you would die.

Love to hear any thoughts on this subject!

EDITS:

**Immortality**

I'd like to note that when I say "immortality" I am using the definition of "non-aging but able to be killed by other means, such as disease or a fatal wound".

I think that this is an important distinction. Although it is (IRL) technically possible to die at any moment due to a freak occurrence or accident, most people tend to assume they will live to a certain age. 

In this scenario, there is no "expected" age to which someone will live; they could suddenly die of cancer at age 20 or live to be hundreds of years old. Age at time of death wouldn't follow a predictable distribution around the mean/median. This unpredictability is what I think would have interesting implications.

**Cancer**

The vast increase in cancer risk would be for a specific type of malignant, quickly-progressing cancer which is very rarely seen nowadays. Otherwise, as pointed out below, everyone would die of cancer fairly early. Sure, this isn't exactly how a classic mutagen works but since it's a theoretical pharmaceutical we can bend the rules a bit.

Thanks for the thoughts so far!