Cancer Genetics
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By Stephen Ornes

Cracking Cancer’s Code

Genetics is key to unlocking cancer’s causes

By Stephen Ornes


Since human beings first documented cancer nearly 4,000 years ago, we’ve been looking for the cause. Ancient Egyptians blamed the gods; some Victorians blamed sadness. Hippocrates, the ancient Greek doctor often cited as being “the father of medicine,” said cancer arose from an excess of black bile in the body—an idea that stuck for more than a thousand years. Despite wayward investigations and pervasive myths, scientists now know that the roots of cancer run deep in the human body: All cancer arises from the interactions of multiple genes, or the interactions of genes and the environment. In other words, all cancer is genetic.

This is why a growing area of research is looking at cancer’s instruction manual. Nearly every cell in the body contains a complete set of instructions for how to make a human—instructions that are made up of genes. Genes, in turn, are made of deoxyribonucleic acid, or DNA, which contains the recipe for building proteins. Proteins work together like tiny machines to make cells do their jobs. Paradoxically, that same instruction book that contains the directions for how to make a human work also contains the recipe for diseases like cancer.

With a better understanding of how tumor formation is triggered by genetic mutations—changes in DNA that alter a gene’s function—scientists hope they will be able to find ways to help people. Oncologists could use genetic tests to help make diagnoses, while biostatisticians could use an awareness of a person’s genes to calculate his or her risk of certain cancers. Some genetic screening tests already exist: Women who inherit mutations in a gene called BRCA1 or BRCA2, for example, may be five times as likely to develop breast cancer; other tests can screen for genes related to colon and thyroid cancers.

Some new cancer drugs also take advantage of genetic information. Trastuzumab (Herceptin), for instance, effectively treats some breast cancer patients whose tumors have a particular genetic mutation. In the longer term, for some cancers, genetics researchers hope to better understand the process by which mutations lead to tumors—and perhaps cut off the disease before it even gains a footing.

Scientists have made significant inroads since James Watson, Francis Crick, Rosalind Franklin and Maurice Wilkins mapped out the structure of DNA in 1953, but the science still has a long way to go. So far, genetics research hasn’t delivered many life-saving tools. It has, however, delivered hope: Many of the applications of cancer genetics to cancer prevention, diagnosis and treatment have started to yield promising results. And the next generation of research promises to be a formidable ally in the fight against cancer.


Parents vs. Environment
Cancer may not be contagious—but can a person catch it from his parents? All human beings inherit their genetic material from their parents. If both parents have a mutated form of a gene, for example, then their children are guaranteed to have the same mutation. If that mutation plays a pivotal role in the development of cancer, the person may be at increased risk for the disease. More generally, if cancer shows up multiple times in a person’s ancestral line, then the person may expect to face an increased risk.



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