The US Food and Drug Administration has approved the drug pemetrexed (Alimta) for treatment of non-small cell lung cancer. People with stage 3 or 4 cancer who already have had unsuccessful chemotherapy are eligible to try it.

Although pemetrexed has not been shown to improve survival, it appears to be as effective as the usual second-line treatment, docetaxel, but with fewer side effects.

That could translate into improved quality of life for patients with a disease that is very difficult to treat, said Len Lichtenfeld, MD, head of the Cancer Control Sciences department at the American Cancer Society.

"Unfortunately, neither drug is a cure for recurrent lung cancer," he noted.

Lung cancer is the most common cause of cancer death among men and women in the United States. Nearly 174,000 people will develop the disease this year and more than 160,000 will die from it. Smoking is responsible for most cases of lung cancer, but non-smokers also can develop the disease.

Alimta works by blocking 3 enzymes the lung cancer cells need to survive, manufacturer Eli Lilly and Company said in a statement. However, the drug also affects the nutrient folate, so patients must take a folic acid and vitamin B12 supplement while they are in treatment.

The vitamins help lessen the drug's side effects, which include decreases in infection-fighting white blood cells, decreases in blood platelets, and anemia. Alimta can also cause liver problems, diarrhea, and fatigue. In the clinical trial on which the approval was based, these side effects were less severe with Alimta than with docetaxel.

Alimta is given by infusion once every 3 weeks.

The drug is also approved to treat malignant pleural mesothelioma, another type of cancer associated with asbestos exposure.