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Comment by sniperjoe360 | Hacker News Reader

As an oncologist, the cause is unknown. But it's not so simple to point fingers at one cause. For example someone who is a heavy smoker (ie. a pack a day) gets cancer at a rate of 25% in their lifetime should they live to age 80. It's a delicate interplay between genetics, development, and environment. We should identify all modifiable risk factors and change our behavior to reduce exposure to them.

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A 2022 study claims that a combination of vitamin D supplements, Omega-3 fatty acid supplements, and (mild/moderate) exercise reduces cancer risk by 60% or so for older adults, but the same factors apply to young people as well.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9261319/

I could easily believe that lack of sunlight (vitamin D) and exercise accounts for almost all of the observed increase.

Screen-associated pastimes strike again!

> lack of sunlight

Might be actually too much if the increase is caused by skin cancers.

If you read the article, you’ll find there is zero mention of skin cancer, it’s mainly concerned with GI tract, liver and kidney cancers.

It seems that many (maybe most) cancers are kicked off by inflammation, or otherwise stressed tissues, after the conditions are just right (genetics, carcinogen, or otherwise damaged dna). Cells that are damaged enough to spread as cancer can avoid getting replicated for years or even never without a trigger. So, it could be that we aren't more exposed to carcinogens, but more frequently encounter the conditions that make the damaged cells start spreading. So, vitamin-D and Omega-3 could indeed help in that regard, and some other cause of chronic inflammation could be responsible for the upward trend.

Yes, you are exactly correct! Vitamin D and exercise share a common result. They both increase and maintain our body’s growth hormone production at healthy levels which is the prime driver of a healthy T cell cancer/virus killing immune system function!! Chronic growth hormone deficiency is at epidemic levels in adults and increasingly in young adults that is weakening our killer T cell immune system function and causing cancer at unprecedented levels!! Sadly, most physicians who read this will roll their eyes because they think they know it all! If they did we wouldn’t have such record levels of disease and death today!!

> For example someone who is a heavy smoker (ie. a pack a day) gets cancer at a rate of 25% in their lifetime should they live to age 80

I'm curious what the odds are for an 80 year old light or never smoker. Is it 24%? 2.4%? .0024%? Do you know?

Also curious how long you have to live as a non smoker to get to that equivalent 25%. I'm under the impression that everyone gets cancer if you live long enough.

Odds for a never smoker aren't well estimated, but I'd say it's in the single digits. Definitely less than 5%. It depends on one's radon exposure, asbestos exposure, exposure to gas stoves/coal burners, smog pollution, and genetic background. Many lung cancers in non-smokers are driven by single gene alterations (i.e. EGFR, ALK)

Your second question is also interesting. For a nonsmoker to get to 25% lung cancer risk, I guess he/she would have to live past 80, which few people do.

Your statement that we all probably get cancer eventually is mostly true - as we age there is an accumulation of mutations which eventually should cause cancer. Some super-elderly people in their 90s and 100s may have more senescent cells than others, and paradoxically lower their risk of new cancer later in life.

What are some things that are known to be uncorrelated if any?

Hmm. The young aren't smoking much these days. But they are often vaping. What's the data on vaping as a cause of cancer?

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