65% of Cancers Caused by Bad Luck, Not Genetics or Environment

BarbaraHudson writes The Wall Street Journal and the CBC are reporting that about two-thirds of cancers are caused by random chance. From the WSJ: "The researchers, from the Johns Hopkins University School of Medicine in Baltimore, analyzed published scientific papers to identify the number of stem cells, and the rate of stem-cell division, among 31 tissue types, though not for breast and prostate tissue, which they excluded from the analysis. Then they compared the total number of lifetime stem-cell divisions in each tissue against a person's lifetime risk of developing cancer in that tissue in the U.S." The correlation between these parameters suggests that two-thirds of the difference in cancer risk among various tissue types can be blamed on random, or 'stochastic,' mutations in DNA occurring during stem-cell division, and only one-third on hereditary or environmental factors like smoking, the researchers conclude. 'Thus, the stochastic effects of DNA replication appear to be the major contributor to cancer in humans.'" The CBC reports: "The researchers said on Thursday random DNA mutations accumulating in various parts of the body during ordinary cell division are the prime culprits behind many cancer types. They looked at 31 cancer types and found that 22 of them, including leukemia and pancreatic, bone, testicular, ovarian and brain cancer, could be explained largely by these random mutations — essentially biological bad luck. The other nine types, including colorectal cancer, skin cancer known as basal cell carcinoma and smoking-related lung cancer, were more heavily influenced by heredity and environmental factors like risky behavior or exposure to carcinogens. Overall, they attributed 65 percent of cancer incidence to random mutations in genes that can drive cancer growth."

Comments

Re:mostly bullshit

[Bengie]

I think you missed the part about 65% and not "all" cancers, and some cancers are highly affected by carcinogens and some are less based on biases created in modern living.

Re:mostly bullshit

[Hartree]

So, you're saying you're a lawyer?

actual paper

[kharchenko]

Here's a link to the actual paper, and a pretty nice editorial from Science (as opposed to CBC).

Environmental Factors?

[m00sh]

The summary says,

The correlation between these parameters suggests that two-thirds of the difference in cancer risk among various tissue types can be blamed on random, or 'stochastic,' mutations in DNA occurring during stem-cell division, and only one-third on hereditary or environmental factors like smoking, the researchers conclude.

The article says,

By “chance” Tomasetti meant the roll of the dice that each cell division represents, leaving aside the influence of deleterious genes or environmental factors such as smoking or exposure to radiation.

The summary says 1/3 has smoking and environmental effects, while the article says the 1/3 doesn't have smoking and environmental effects.

Lately, slashdot summaries have gotten worse and worse and completely change what is being claimed.

Initiators vs promoters

[manu0601]

The headline is shocking when one consider the steep rise of cancer since 1945. If it was luck, then how it could change over time?

But I think the paper could still be a valuable contribution, it is just that this summary ignores the difference between cancer initiation and cancer promotion. Many environmental factors favor existing tumors but do not create them. Hence initiation can be random, while promotion can be environment-induced.

Re:Initiators vs promoters

[x0ra]

The world population almost doubled since 1940 (http://en.wikipedia.org/wiki/World_population), not to mention our capacity to detect smaller and smaller tumors made the number explode. Before, people were dying, not they're dying from a diagnosed X or Y reasons. Not to mention our lifespan increased, which increased the likelihood of our body's to go AWOL.

Re:Initiators vs promoters

[stoploss]

You seem to misunderstand: cancer requires more than a single mutation. At a bare minimum cancer needs a protooncogene mutation, and then typically also requires Knudson two-hit on at least one of the tumor suppressor genes. That, together, gets cancer started.

The angiogenesis and metastasis mutations (among others) happen later due to natural selection. Cancer is just evolution.

To restate: I have never heard of a single DNA point mutation from wild type that can cause cancer. Multiple mutations of specific types are required. The odds of this happening are increased because most adult cells are on "pause" in the cell cycle, so mutations can accumulate without causing immediate triggering of apoptosis.

Re:mostly bullshit

[Kjella]

Oh please, there are so many billions of people living wildly different life styles and there's a considerable incidence of cancer all of the world. And we got cases of cancer that are 3000 year old, it's not like it showed up recently. And if you correct for increased lifespan there's no explosion in cancer, we only have a lot more old people whose cell reproduction system has had longer to develop a critical fault. Obesity is a contributing factor to heart problem, there's still normal weight/underweight people with heart problems. I don't know any rational basis to assume the default is almost no cancer and it all must be part of some conspiracy, but apparently the tin foil hatters are modding you up. I guess they can mix the cancer-giving stuff into the chemtrails...

Sorry, I believe in a just world

[Anonymous Coward]

I must believe that when people get cancer, it is solely due to a personal failing, like smoking, poor diet, lack of exercise, drug use or obesity. Then I can blame them personally and feel good knowing that it can't happen to me because I don't commit any of those vices. Nor should society, aka me, have to pay for their cancer through higher insurance rates or government taxes because cancer patients are simply reaping what they have sown! The made the wrong heath choices, they should face the consequences.

Context matters

[Okian Warrior]

The headline is shocking when one consider the steep rise of cancer since 1945. If it was luck, then how it could change over time?

You're forgetting the context in which the study was made.

By assigning most cancer to random chance, they are laying the groundwork for the defense against future lawsuits for negligence and compensation against corporations. Companies will pour money into shouting these results as widely and loudly as possible, it will become a public meme, and the populist mantra will be "I got cancer, but it was just bad luck" for decades.

This is similar to the recent history of the tobacco industry, it took over 50 years to sort that out and the damage hasn't yet settled.

Expect this report to be wildly popular for the next few years.