Personalized medicine becoming a reality

Imagine this in the not too distant future -- you go to the doctor and he finds out that you have a serious illness. To figure out what the best medicine for you might be, he reads some of your DNA. He finds that your illness would best be treated with a certain medicine and that your body will tolerate it well. Because you got the right medicine, you are cured with very few side effects. Is this coming soon to a doctor's office near you? Maybe sooner than you realize. Medicines work differently for different people. For example, one drug may cure one person but have no effect or even kill another. The answers to why medicines work better or worse in people can be found in their DNA. Everyone's DNA is a little different. These differences can sometimes mean that your body will handle drugs in different ways. In other words, how well a drug works is dependent on who you are. The problem becomes even more pronounced in cancers. Cancers have many, many DNA changes that are different from the rest of the body. Everyone's cancers share some of these mutations and may also have unique ones of their own. What this means is that there are lots of different types of cancer. For example, not all breast cancers respond to the same chemotherapy because they have different changes in their DNA. So being diagnosed with breast cancer might not be information enough for the doctor to prescribe the right medicine. The two articles below deal with how different types of cancers respond to different drugs. Both find that the specific sequence of DNA found in these cancers affects whether an anti-cancer drug would be effective or not. With more findings like these, the era of personalized medicine may soon be upon us.
Subset of lung cancer patients helped by Iressa
Would you take a medicine that only helps 1 in 10 people? Your answer might change if the doctor could tell you if you were that 1 in 10. This now might be the situation with Iressa, a drug that effectively treats about 10% of lung cancer patients. Scientists think that they now might be able to figure out who will be helped by Iressa based on the DNA in the patient's particular cancer. Iressa stops cancers from growing by keeping a protein called epidermal growth factor receptor (EGFR) from working. Apparently, those who responded well to Iressa had DNA changes in the EGFR gene. These changes make the cancers so dependent on EGFR that once Iressa starts working, these cancers can't find another way to grow and so they disappear. Once a test for this DNA change becomes available, doctors may quickly be able to tell whether Iressa might help you. Until then, if you are Japanese, a woman, and/or a nonsmoker, there is a good chance Iressa may work for you as these mutations were more common in this population.

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Cancers that refuse to die
Why does chemotherapy work for some cancer patients and not others? Since cancers are all so different, there are probably lots of different reasons. For at least one type of leukemia, scientists may have figured out why chemotherapy sometimes doesn't work. The most common form of leukemia in the U.S. is chronic lymphatic leukemia (CLL). Apparently, patients with CLL who have a certain DNA change do not respond well to chemotherapy. This DNA change tells the cancer cells to keep growing even though they have been damaged by the chemotherapy. Chemotherapy usually works by damaging the cancer cells so severely that the cancer cells end up killing themselves. The way the body eliminates damaged cells is a process called programmed cell death or apoptosis. Apoptosis involves the cell recognizing it has a lot of damage and killing itself before it can do any harm. This process is under pretty strict control to keep cells from living too long or prematurely killing themselves. In resistant CLL, one of these controls has been changed so that the cancerous cells keep living after being damaged.