COLUMBIA, Md. (AP) ¿ Celsion Corp., which makes heat activated treatment systems for cancer, said Tuesday the Food and Drug Administration granted "orphan drug" status to its developing treatment for liver cancer. Shares of Celsion surged 51 cents, or 21 percent, to $2.89 in morning trading. The stock has traded between $1.60 and $6 over the past 52 weeks. The designation, for Thermadox, gives the company a range of incentives while developing the drug candidate. Orphan drug status is typically given to developing treatments aimed at rare conditions or conditions that have a lack of treatments on the market. The incentives include seven years of market exclusivity following FDA approval, FDA assistance in clinical trial design, a reduction in FDA user fees, and tax credits. Primary liver cancer is one of the most deadly forms of cancer and ranks as the fifth most common solid tumor cancer, the company said. There are about 20,000 cases per year in the United States.