Lung cancer is a big topic at this year's American Society of Clinical Oncology meeting. It isn't exactly the easiest disease to treat, so any positive data is great news for investors.

Eli Lilly's (NYSE: LLY) Alimta is already approved to treat lung cancer, but data presented at ASCO suggests that using the drug longer can help keep the cancer at bay. After an initial treatment with Alimta, patients who continued on the drug saw their disease progression delayed by 1.3 months compared to those who got placebo after the initial treatment. Convincing doctors to use Alimta as a maintenance therapy should help increase sales of the $2 billion-plus drug.

Pfizer's (NYSE: PFE) crizotinib isn't approved yet, but some analysts are already calling for a potential $2 billion or more in revenue. I'm not convinced it'll get that high, but there's little doubt that crizotinib will be approved. More than half of the patients taking crizotinib were alive after two years, which is rather remarkable compared to around 12% who survive that long taking standard therapy.

The problem for Pfizer is that crizotinib is designed to treat patients who have a certain mutation that only occurs in 4% of lung cancers. Pfizer will be able to charge a premium for the drug, but obtaining $2 billion in sales might be stretching it, given the limited patient population.

Celgene's (Nasdaq: CELG) Abraxane shrinks lung tumors, but it hasn't been shown to extend overall survival. Abraxis, which owned the drug before Celgene bought it, obtained a special protocol assessment -- the Food and Drug Administration signed off on the trial design -- so an approval seems likely. It remains to be seen whether the lack of survival data will hamper sales though.

Farther back in the pipeline, OXiGENE's (Nasdaq: OXGN) Zybrestat when added to Roche's Avastin and chemotherapy didn't delay progression of the disease in the entire treatment population. But the drug does seem to be helping patients with a poor performance status. The phase 2 trial certainly won't be enough to get the drug approved, but it does seem like a strong enough signal to push into a phase 3 trial in the subset of patients with a poor prognosis.

Interested in small companies? Grab this free report from Motley Fool analysts: "Too Small to Fail: 2 Small Caps the Government Won't Let Go Broke."

Fool contributor Brian Orelli holds no position in any company mentioned. Click here to see his holdings and a short bio. Motley Fool newsletter services have recommended buying shares of Pfizer. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.