The role of maintenance pemetrexed in the treatment of non-small-cell lung cancer.

Until recently, the weight of evidence has supported the discontinuation of chemotherapy in advanced non-small-cell lung cancer (NSCLC) after 4-6 cycles of induction therapy. This allows patients with limited life expectancy a "treatment holiday." A minority of cases then go on to receive second-line therapy, although many deteriorate rapidly and never receive further active treatment. There has been renewed interest in the concept of maintenance from trials with pemetrexed and erlotinib. Both these agents can be given for long periods without serious cumulative toxicity in most patients. Both trials have shown significant extension of progression free survival in placebo-controlled trials. In cases who are not receiving pemetrexed as induction therapy, a statistically significant 5-month prolongation of overall survival in nonsquamous NSCLC has been reported. Treatment was well tolerated. This effect may reflect the early administration of an active second-line agent and it remains to be seen whether similar benefits will accrue to patients having pemetrexed as induction therapy.