Lung cancer is the primary reason for cancer related mortality in the world. Although initial treatment for early stage Non-small Cell Lung Cancer (NSCLC) is a complete surgical resection, the recurrence rate of NSCLC in its early stages remains high. Even after a complete resection, the 5-year survival rates range from 67% to 23% for Stage IA to Stage IIIA disease, respectively. Recurrences, which are the primary factor for reduced survival rates, generally occur at distant, extra thoracic sites. As a result, even within its early stages, NSCLC is considered as a systemic disease at diagnosis and further improvement in survival rate can only be achieved with the eradication of micrometastatic disease to reduce the risk of distant recurrences.
Several recent phase III trials provide robust evidence for chemotherapy in adjuvant settings. In the meta-analysis of these trials, pooled analysis of LACE, cisplatin based adjuvant chemotherapy showed 5.4% of absolute benefit in 5-year survival rates. The effectiveness of the chemotherapy strongly depends upon the stage of the disease as well as the performance status of the patient. While patients with performance scale 0-1 gain significant overall survival (OS) benefit from chemotherapy, one should be very careful about patients with performance scale of 2 or greater. There were significant OS benefits for stage II and III disease, while chemotherapy may have detrimental effects on OS in Stage IA patients. Based on the subgroup analysis of CALGB 9633 trial, adjuvant chemotherapy may be offered to Stage IB patients with a big tumour.
Further improvements can be achieved by defining reliable and clinically approved predictive and prognostic factors and tailor treatment by using these parameters. RAS, p53 ERCC1, and gene expression profiles are all seemed to be reliable predictive and prognostic factors, but to the best of the authors' knowledge, there are no prospective data to support routine their clinical use.