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.

actual paper

[kharchenko]

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

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.