For the first time in a decade, an experimental drug has extended the life of patients with advanced lung cancer who relapsed after standard chemotherapy.

But the benefit in the study was so small – six extra weeks, on average – that it is raising fresh questions about the value of some costly new cancer medicines.

Eli Lilly and Co.’s drug Cyramza was tested in more than 1200 patients.

It is now sold for stomach cancer and costs $US6,000 ($A6,491.75) per infusion.

The study was discussed on Saturday at a cancer conference in Chicago where doctors also reported progress with new drugs against relapsed ovarian cancer and chronic lymphocytic leukemia, the most common type of leukemia in adults.