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Comment by ktRolster | Hacker News Reader

This is weird:

  >Until the late 1930s, stomach cancer was 
  >the No. 1 cause of cancer deaths in the 
  >United States.

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In countries which still practice wide-scale pickling, curing and fermentation -- stomach cancer rates are still very high.

http://www.reuters.com/article/us-salty-diet-idUSTRE62N4KX20...

While gastric cancer is declining, it is still the most common cancer in Korea. Past studies have yielded conflicting results as to whether a salty diet causes gastric cancer, though most found an association between salt use and gastric cancer.

Here's another piece of information: https://en.wikipedia.org/wiki/Refrigerator

The introduction of Freon in the 1920s expanded the refrigerator market during the 1930s. Home freezers as separate compartments (larger than necessary just for ice cubes) were introduced in 1940.

That's a good point, but it's probably the organic acids rather than the salt (which the media report you've linked to blames). Bacteria which produce lactic acid are primarily used for traditional fermentation, I think, whereas distilled vinegar is made from ethanol by bacteria that produce acetic acid...

Hmm:

"Compared to acetic acid, [lactic acid's] pKa is 1 unit less, meaning lactic acid deprotonates ten times more easily than acetic acid does. This higher acidity is the consequence of the intramolecular hydrogen bonding between the α-hydroxyl and the carboxylate group." - https://en.wikipedia.org/wiki/Lactic_acid (emphasis added)

I found a chart showing the prevalence of multiple forms of cancer over time: http://i52.tinypic.com/r9euci.jpg.

Not sure what the source is on that chart, but I'll assume it's credible. If that's the case, then despite what the article says, it's hard to believe that most of this decline is not accounted for by the decline in smoking. Surely the decline in smoking accounts for the vast majority of the lung cancer decline, and the peaks for colon and prostate cancer are very close to the same time.

Smoking also increase the time it takes to recover from surgery fwiw

Wooow! That's lot of lung cancer deaths, counterintuitively coupled with air pollution elimination.

I wonder how this correlates not with tobacco smoking, but especially with smoking of factory-made cigarettes? Because as I understand those contain virtually no tobacco and you end up smoking garden fertilizer-soaked paper.

Weird. Why would lung cancer go the opposite direction as smoking prevalence? I understand the dynamic of "cancer only kills people who outlive every other cause of death", but for the discorrelation to be that strong?

smoking rates was dropping quickly since 1945, during the period lung cancer rates were going up significantly.

death is a bad stat to look at; incidents would be more useful

If I were to guess, the results lag behind the prevalence. It takes many years for someone to get cancer. If you were to push back the graph by 20 years it may correlate strongly.

Edit: Also, the U.S. banned asbestos in 1989. That's the turning point of the graph.

The correlation is one of the strongest there is, and indeed, causal -- there's a almost perfect lag time of ~20 years [1].

[1] https://en.wikipedia.org/wiki/Lung_cancer#/media/File:Cancer...

The graph stops at 1970.

Are you suggesting that some post-Nixonian mechanism is in play here.

People die from lung cancer when they are a bit older, so it's shifted to the right relative to the prevalence of smoking.

Widespread refrigeration removed the need for cured and salted meats. This is widely thought to explain the discrepancy.

In the later 50's the FDA also put strict limits on the amount of sodium nitrite allowed in cured meats. And required the addition of ascorbic acid. The latter supposedly neutralizes the nitrite when the meat is heated/cooked.

Does that take into account refrigeration? Maybe it's totally unrelated --but prior to refrigeration a lot of meats were cured.

The article suggests several possibilities, including increasing use of antibiotics, and less consumption of salted/cured meats, but the actual answer is unknown.

And actually that is the crux of the article: it's not that doctors aren't thinking of possibilities to explain the reduction in disease, they just don't know for sure which of the possibilities they are.

Basically, if we've thought of a possibility in the last 20 minutes since reading the article (or headline), a doctor has probably already thought of it, too.

True enough. One other thing is also the decline of "elixirs" with unknown ingredients, chemicals of then unknown toxicity.

stomach cancer was spiked due to h-pylori. water treatments put a huge dent in that

A comment like this could be very insightful, but you didn't mention what h-pylori is, or why water treatments help reduce it.

The cool thing about the internet is there's a whole universe of information at your fingertips: https://en.wikipedia.org/wiki/Helicobacter_pylori

I read an blog entry by a retired surgeon. He said when he started a lot of his bread and butter business was surgically fixing ulcers. Then came drugs to reduce stomach acid, followed by the discovery of Helicobacter pylori, and that business mostly went away.

It's the bacteria that causes stomach ulcers.

It was mentioned in the article: "H. pylori, the bacteria that can cause stomach cancer"

Currently, South Korea and Japan have the highest incidences of stomach cancer. It's typically attributed to cured foods and processed meats. Prior to refrigeration, wide consumption of these foods were out of necessity.

I bet it's related to smoked fish and other smoked food products.

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