Though the pharmaceutical industry is struggling with what will likely be its least productive year in terms of new drug approvals, its pipeline is growing, particularly in the area of new cancer therapeutics. A report from the end of 2006 from the Pharmaceutical Research and Manufacturers of America finds biopharmaceutical companies are working on a total of 646 cancer medicines now in the clinic or under review by the U.S. Food and Drug Administration. This includes both new drugs in development and the pursuit of new uses for existing drugs. Not counting drugs targeting solid tumors, lung cancer tops the list with 96 drugs in development. That’s followed by breast cancer with 79 drugs. Despite progress in recent years, cancer remains second only to heart disease as the leading cause of death in the United States. This year about 565,000 people in the United States will die from various forms of the disease.