PROSTATE CANCER: ENVIRONMENT PLUS GENETICS EQUALS
Genetic Susceptibility
Most important about these findings is that they firmly establish prostate cancer as a disease that, like breast and colon cancer, is due at least in part to genetic susceptibility.
The theory here is that cancer doesn’t just happen overnight; a whole chain of genetic events must occur—picture a whole row of dominos being overturned—before a tumor can begin to grow. Some men may be born with part of the chain completed. “If you inherit some of these steps,” says one molecular biologist at Johns Hopkins, “then you’ve shortened the time it’s going to take to accumulate all of them.” So inherited mutations in one or more genes probably speed up the body’s journey toward cancer, and that’s why these men develop their cancer at an earlier age. Environmental factors— variables such as diet—may do the rest.
This is what scientists think happens on a genetic level to make cancer possible: Mutations occur in the genes that regulate normal cell growth. When one of these genes is mutated, by whatever it is that causes cancer, the cells begin to grow at an abnormal rate. For example, some of these mutated genes, called oncogenes, when activated, become switches that work like a stuck accelerator in a car. They’re mutated in such a way that they can’t be turned of reason in a cell cycle that can easily get out of hand. Their purpose seems to be to put on the “brakes”—to control cell division. Most cancers require that one or more of these checkpoint genes be knocked out—either mutated or completely obliterated— before a cell can become malignant. Thus, the mutations that lead to the development of prostate cancer may involve a process in which the accelerator is stuck and the brakes have been removed, and cell growth is out of control.
The segment of cancers caused solely by environment, like that of purely inherited cancers, is believed to be small, about 5 percent. “If you knock out each end of the spectrum,” says the molecular biologist, “the 90 percent of cancers in between are probably due to some sort of interaction between what you eat and smoke and get exposed to, and how your genetic predisposition handles everything.”
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Tagged as: Erectile Dysfunction, Men’s Health
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