blackbearnh writes "Until recently, physicians prescribed drugs to patients with dosages based only on weight, and with no idea if the drug would be effective for that particular person. But as this article on Forbes.com highlights, the same advances in genomics that are letting people know about their likelihood of getting certain diseases can also let doctors know what drugs, and what dosages, will be likely to do the most good. 'Tamoxifen, the much-heralded cancer-fighting drug, has been shown to have little benefit for 7% to 10% of patients taking it. In the past, we would have just said that it works 90% of the time. But now, with our new genomic knowledge under our belt, we can say that it works nearly 100% of the time for people with the 'right' version of the CYP2D6 gene, and 0% of the time for people with the 'wrong' version, who make up roughly 7% to 10% of the population.'"