A new study says there’s an increased risk of leukemia in breast cancer patients who take Amgen’s Neulasta and Neupogen. The Columbia University study showed that close to 2 percent of those who took drugs to increase white blood cells later developed acute myeloid leukemia, as compared with only 1 percent of the women who didn’t take the treatment. But as is typical in these studies, not everyone agrees. Some analysts say that the study does not properly differentiate on the role that elevated levels of chemotherapy or radiation might have played. Another potential flaw, say the experts, is that the study was conducted only among women over 65. Wall Street apparently wasn't too bothered - shares of the Thousand Oaks-based biotech giant gained 34 cents, to close at an even $70.