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Tumor DNA studies help explain cancer genetics

March 28, 2013|By Eryn Brown
  • A scanning electron microscope image of a breast cancer cell. Now, using DNA sequencing techniques, researchers can peer even deeper into tumors to understand their genetics.
A scanning electron microscope image of a breast cancer cell. Now, using… (National Cancer Institute )

As it has become more efficient and less expensive to analyze the DNA in normal cells, it has also gotten a whole lot easier to analyze the mutated DNA in tumors — a project scientists hope will help explain why cancer behaves as it does and what new strategies oncologists might use to stop its growth.

Writing in a special section of the journal Science (available for free with registration) on Thursday, researchers distilled much of what they’ve learned from tumor sequencing so far. In this review article, Johns Hopkins cancer geneticist Kenneth Kinzler and colleagues looked at the results of more than 100 cancer genome sequencing projects to compile a list of just a few general principles about the disease. To paraphrase a few:

While many cancer cells display large numbers of mutations, most cancers are caused by just a few alternations in DNA, which develop over the course of 20 to 30 years. 

Every tumor is genetically unique, but the cellular processes affected in different tumors are similar.

Genes known to drive cancer growth are involved in three basic cellular functions, determining cell fate, monitoring cell survival, or maintaining the genome.

The cells in individual tumors are not all alike — and their differences may contribute to resistance to treatment.

The co-authors argued that an optimal approach to fighting cancer would try to seek out these genetic changes in tumors before a cancer becomes advanced and spreads throughout the body. Such an approach would require increased investments by governments and philanthropic groups, they said.

“We believe that cancer deaths can be reduced by more than 75% in the coming decades, but that this reduction will only come about if greater efforts are made toward early detection and prevention,” they wrote.

Additional articles in the special section on cancer genomics focused on ramifications for patient treatment, drug development and scientists’ understanding of normal and abnormal cell development.

Readers interested in a different kind of cancer genetics analysis — the type that looks at people's DNA to assess their inherited risk for the disease — might also take a look at a series of studies describing results of the Collaborative Oncological Gene-environment Study, or COGS, which probed genetic variations in more than 250,000 people. 

Analysis of the mountain of data doubled the number of regions of the genome known to be associated with breast, ovarian and prostate cancers. 

To learn more about COGS, read the Los Angeles Times coverage (accessible through the top related items link, at left.) For the more technically inclined, the Nature journal has created a special Web feature to allow readers to explore the findings in more detail.

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