Maintenance therapy in NSCLC: why? To whom? Which agent?

Lung cancer is the leading cause of cancer mortality in USA and worldwide more than one million people die from this disease every year: the overall 5-year relative survival rate measured by the Surveillance Epidemiology and End Results program in USA is 15.8% [1]. Approximately 87% of lung cancer cases are Non Small Cell Lung Cancer (NSCLC) and the majority of patients presents with advanced stage disease at diagnosis [2,3]. In two independent phase III trials the addition of bevacizumab to standard first-line therapy was shown to improve both overall response rate (ORR) and PFS, although OS advantage was demonstrated in only one of these studies [4,5]. In combination with platinum-based chemotherapy, cetuximab has also demonstrated a small statistically significant OS advantage as compared to chemotherapy alone [6]. Second-line treatment has been shown to improve survival and to palliate symptoms: approved treatment options include cytotoxic chemotherapy (docetaxel or pemetrexed) or epidermal growth factor - EGFR tyrosine kinase inhibitors (erlotinib or gefitinib) [7,8]. However, only approximately 50% of the patients will be able to receive second-line therapy, mainly because of the worsening of clinical conditions [9].One of the strategies, that has been extensively investigated in recent years in order to improve current clinical results in advanced NSCLC, is the maintenance therapy. Here, we review available data on maintenance treatment, discussing about the possibility to tailor the right treatment to the right patient, in an attempt to optimize costs and benefits of an ever-growing panel of different treatment options.The U.S. National Cancer Institute's medical dictionary defines maintenance therapy as "any treatment that is given to keep cancer from progressing after it has been successfully controlled by the appropriate front-line therapy; it may include treatment with drugs, vaccines or antibodies, and it should be given for a long time". Maintenance th