document: Cancer genomics Throughout life , the cells in every individual accumulate many changes in the DNA inherited from his or her parents . Certain combinations of changes lead to cancer . During the last decade , the cost of DNA sequencing has been dropping by a factor of 10 every two years , making it now possible to read most of the three billion base genome from a patient 's cancer tumor , and to try to determine all of the thousands of DNA changes in it . Under the auspices of NCI 's Cancer Genome Atlas Project , 10,000 tumors will be sequenced in this manner in the next few years . Soon cancer genome sequencing will be a widespread clinical practice , and millions of tumors will be sequenced . A massive computational problem looms in interpreting these data . First , because we can only read short pieces of DNA , we have the enormous problem of assembling a coherent and reliable representation of the tumor genome from massive amounts of incomplete and error-prone evidence . This is the first challenge . Second , every human genome is unique from birth , and every tumor a unique variant . There is no single route to cancer . We must learn to read the varied signatures of cancer within the tumor genome and associate these with optimal treatments . Already there are hundreds of molecularly targeted treatments for cancer available , each known to be more or less effective depending on specific genetic variants . However , targeting a single gene with one treatment rarely works . The second challenge is to tackle the combinatorics of personalized , targeted , combination therapy in cancer .
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