Shares of Insys Therapeutics (NASDAQ:INSY) rose 20% today, after the company posted strong second-quarter results for its cancer-related pain medicine, Subsys. After operating at a loss last year, the 38% sales growth of the drug this year helped propel Insys to making a $24 million profit this year. Shares of the stock have doubled year to date and are up 600% over the past 12 months.

In this video, Motley Fool health-care analyst David Williamson looks at Insys. With sales of Subsys having now surpassed all estimates, this is one that he will definitely have on his radar going forward.