The Obama administration has decided that Medicare will pay for one of the newest, most expensive cancer medications, which costs about $178,000 for a standard course of treatment. Patients, doctors, hospital executives and insurers have expressed concern about the high cost of prescription drugs, especially new cancer medicines and treatments tailored to the genetic characteristics of individual patients. Medicare officials recognized the cost and value of one such product, the anticancer drug Blincyto, by agreeing to make additional payments for it starting Oct. 1. The drug is made by Amgen for patients with a particularly aggressive form of leukemia.