Eating fish may cause melanoma

(Edith) #1

It’s nice to know that beef is no longer alone as a cancer causing agent.

(Joey) #2

Didn’t bother reading the link, but I suspect that rubbing fish scales on oneself might induce a range of unpleasant skin reactions.

(Bob M) #3

It is good to see something that’s supposedly great for you get taken down. Would love to see olive oil have this treatment.

But the actual risk is amazingly small, like 0.22%, if my calculations are correct (and they probably aren’t, since I don’t have access to the whole paper and also I forget exactly how hazard ratios are defined).

This is where they got their data:

Not sure anything good can be gotten from this type of data. Unless the hazard ratio was > 2.

(Todd Allen) #4

Like most if not all studies giving beef a bad reputation this study is also merely observational and nothing was done to test the observations. The quality of data informing the observations is likely poor in this case as it was based on a food survey at the start of the study with no ongoing tracking of their dietary changes over the years nor with any attempt to ensure or evaluate the accuracy of the initial survery responses.

It also seems questionable they only found the weak correlation for non-fried fish. As long as the fish is deep fried there is no association with skin cancer?!? I’d like to hear the arguments for the benefits of deep frying…

(A fool and his bacon are soon parted) #5

Austin Bradford-Hill would agree with you. He famously said that a hazard ratio under 2.0 wasn’t worth bothering with, and made that one of his famous criteria.


I wonder if it’s because very little fish is wild caught anymore and are all farmed, and how do they prepare it and package it for shipping and storing? Maybe it’s the chemical additives or polluted waters and not the actual fish.

I bet if I went out on open healthy waters and caught my own, skinned and deboned it and cooked it that same day it wouldn’t have these risks at all. Lol. I do miss all the fish of my childhood when we used to camp in Wisconsin. I haven’t had such wonderful tasting fish since.

(GINA ) #7

Or maybe it is because people who live near the beach eat more fish because it is fresh and get more sun because they live by the beach. What a batch of confounders.

It is all just dumb.

(Stickin' with mammoth) #8

Fresh caught fish on our Oregon coast is steep enough to cause my wallet to hyperventilate. I used to want to live close to seafood, now I just want to live close to Paid in Full.

(A fool and his bacon are soon parted) #9

The answer is, we don’t know, and we have no way of knowing from this study.

The study was done at Brown University. The full text is behind a paywall, but the abstract reads as follows:



Prior epidemiological studies evaluating the association between fish intake and melanoma risk have been few and inconsistent. Few studies distinguished different types of fish intake with risk of melanoma.


We examined the associations between intake of total fish and specific types of fish and risk of melanoma among 491,367 participants in the NIH-AARP Diet and Health Study. We used multivariable-adjusted Cox proportional hazards regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).


During 6,611,941 person-years of follow-up with a median of 15.5 years, 5,034 cases of malignant melanoma and 3,284 cases of melanoma in situ were identified. There was a positive association between higher total fish intake and risk of malignant melanoma (HR = 1.22, 95% CI = 1.11–1.34 for top vs. bottom quintiles, p trend = 0.001) and melanoma in situ (HR = 1.28, CI = 1.13–1.44 for top vs. bottom quintiles, p trend = 0.002). The positive associations were consistent across several demographic and lifestyle factors. There were also positive associations between tuna intake and non-fried fish intake, and risk of malignant melanoma and melanoma in situ. However, fried fish intake was inversely associated with risk of malignant melanoma, but not melanoma in situ.


We found that higher total fish intake, tuna intake, and non-fried fish intake were positively associated with risk of both malignant melanoma and melanoma in situ. Future studies are needed to investigate the potential biological mechanisms underlying these associations.

The N is high, which is good, and the p-values are reasonably low, so their results are fairly reliable. The clinical significance, however, is doubtful, since the people in the top quintile had a relative risk of malignant melanoma of 1.22 over the people in the bottom quintile, and a 1.28 relative risk of melanoma in situ over the people in the bottom quintile. So the observed effect, while statistically significant, is clinically barely relevant. As Bob pointed out in his post, there is no way to distinguish a signal from the noise until the relative risk rises to at least 2. Relative risks as low as these are certainly no indication of causality.

Not only that, but how much do you want to bet that they used a food-frequency questionnaire to evaluate the participants’ fish intake?



(Edith) #11

“Using cancer registries, the researchers tracked the incidence of new melanomas over a median period of 15 years, while accounting for other factors that could influence the result, such as sociodemographic factors, [smoking history, family history of cancer,] daily intake of alcohol, daily intake of caffeine and calories, and the average ultraviolet radiation levels in each participant’s local area, per the release.”

“But the authors note the study has some limitations, including the analyses did not account for certain risk factors for melanoma, including mole count, [hair color or history of sun-related behaviors]”

Once again we most likely have a healthy user bias. Those more likely to eat fish, non fried at that, probably spend more time in the sun being active.

“The study recruited 491,367 adults from across the U.S. to the National Cancer Institute’s NIH-AARP Diet and Health Study between 1995 and 1996, with an average age of 62 among the participants.”

I’m thinking only one year of dietary questionnaires?


well when ya read their ‘study suggests’ this hits home:
with an average age of 62 among the participants.

from the net: Age – The risk of melanoma grows as you age. The average age at diagnosis is 65
I think we got very big issues and slant data with this ‘study’ right from the get-go—just ain’t right by any means.

obviously all ages this can be an issue but this ‘wasted useless’ study to me is just crap.

MYTH: There are bugs in your strawberry Frappuccino. This one is no longer used :slight_smile:

  • MYTH: There’s beaver butt secretions in your vanilla ice cream. You
  • MYTH: Coffee stunts your growth. Most research finds no correlation
  • MYTH: Sugar and chocolates are aphrodisiacs.
    I’m using honey as that’s better than sugar. This is a myth.
    Consuming carrots will improve your vision.
    You have to stop eating at a certain time at night to lose weight.
    You should count your calories.
    Red meat causes cancer.
    Don’t eat eggs, ok to eat eggs, DON’T eat eggs, OK to eat eggs…
    pesticides won’t harm ya, they only kill bugs :slight_smile:
    and so on and so on and so on

studies were done on all of the above too :wink:

I can’t take it anymore HA


Life causes cancer. As much time as I spent in the sun slathered in baby oil when I was young, I’m more likely to get melanoma from that. I still garden without sunscreen. I’m 70 years old. If I die soon, I’ll still consider that a good life.


you said it!!

(KCKO, KCFO) #15

I agree, when I lived by the beach, I was a regular at the local fish monger’s shop. Now I have to rely on flash frozen seafoods, I only eat fish once a week or so. I also spent more time out in the sun looking at tidal pools and walking the beaches. I only got to do that for 3 years, so far no skin cancer for me.

I didn’t watch the video, as I never believe anything from with the Fox News logo on it.

(Steve L.) #16

This is another worthless association study that has no way of sorting out the confounding variables and assigning actual causation. It’s worthless.

(Edith) #17

Yes, I know. I found it amusing.