RATIONALE: Studying samples of blood in the laboratory from patients receiving pemetrexed
disodium may help doctors learn more about the effects of pemetrexed disodium on cells. It
may also help doctors understand how well patients respond to treatment.
PURPOSE: This laboratory study is looking at blood samples from patients with stage III or
stage IV non-small cell lung cancer enrolled in clinical trial MCCRC-RC0524 to determine the
effect of pemetrexed disodium on cells.