Eating more fish may be linked to higher melanoma risk | Hacker News Reader

Eating more fish may be linked to higher melanoma risk

scimex.org

10 pointslnyan11 comments

The study doesn’t seem to account for location, as far as I can see. Could it be that people who live by the sea eat more fish, but also get way more Sun at the beach, etc?

The report specifically mentioned it didn’t control for Sun exposure.

This was my first thought. Anecdotally when I lived near the beach I ate a lot more fish due to the availability of fresh seafood.

It's weird how there's a whole thriving genre of studies that look at things with incredibly complicated causal graphs, maybe control for a random smattering of confounding variables, find a correlation between some variables X and Y, and then declare victory -- even though what they found is seldom an actual causal relationship between X and Y, both in theory and in practice [1]. The researchers here at least had the honesty to be forthright about this, but given the limitations of this kind of study I'm not sure I see the point in even doing them.

[1] https://www.gwern.net/Causality

I tend to believe it has a lot more to do with eating fish from cans, mercury, and other industrial contaminants that we overly allow to pollute our waters than specifically the fish itself.

There is already a suspected link between skin cancer and PUFAs, so it could also be that, since fish are rich in those.

> There is already a suspected link between skin cancer and PUFAs […]

No, there isn’t.

The suspected link seems to be a negative one. This paper I found concludes:

Discussion

Our systematic review highlights the dearth of available evidence regarding the risk of skin cancers in relation to dietary omega-3 PUFAs. For SCCs, the combined results of the two informative articles 34,37 showed a nonsignificant 14% reduction among those with relatively high consumption of n-3 PUFAs.

Only one article has addressed the association of fatty fish and melanoma, and it suggested a significant halving of risk in those with diets rich in oily fish. 35 Meta-analysis of the two studies with data available for BCC showed no association between n-3 PUFAs or oily fish and BCC. 36,38

https://pubmed.ncbi.nlm.nih.gov/24265065/

The researchers suspect this as well, though it can’t be concluded based on their data.

A couple of days ago there was an article literally saying that people eating canned fish had lower percentages of cancers.

> The researchers also did not account for some risk factors for melanoma, such as mole count, hair colour, history of severe sunburn and sun-related behaviours in their analyses.

Not controlling for sun behavior is really problematic as that tends to differ in coastal from more continental places which also correlates with fish consumption.

Edit: Crossed with christophilus post who made a similar comment

Is Calamari fish ???.

Reply on news.ycombinator.com