The U.S. Food and Drug Administration has granted fast-track approval to Tarceva (erlotinib) to treat advanced non-small cell lung cancer that has failed to respond to other therapy.

Similar drugs include AstraZeneca’s lung cancer drug Iressa and ImClone Systems’ colon cancer drug Erbitux, both of which try to block a protein that encourages cancer cell growth. The FDA said clinical trials involving 731 patients showed Tarceva appeared to extend life by approximately two months, from an average of 4.7 months among those who took a placebo to 6.7 months. Similar drugs in this class have only been proven to shrink tumors, according to The New York Times.

Tarceva and other so-called targeted drugs tend to have fewer side effects than other cancer treatments, although there have been infrequent reports of serious lung disease among some Tarceva users. Other side effects could include diarrhea, rash, and nausea. And the drug could cause fetal harm to pregnant women, the FDA said.

Non-small cell lung cancer is the most common form of lung cancer in the United States, accounting for 80 percent of cases, the agency said. It noted that it granted approval for Tarceva less than a year after makers OSI Pharmaceuticals and Genentech Inc. submitted the first part of their application in January.