A novel classification of lung cancer into molecular subtypes

Abstract

The remarkably heterogeneous nature of lung cancer has become more apparent over the last decade. In general, advanced lung cancer is an aggressive malignancy with a poor prognosis. The discovery of multiple molecular mechanisms underlying the development, progression, and prognosis of lung cancer, however, has created new opportunities for targeted therapy and improved outcome. In this paper, we define "molecular subtypes" of lung cancer based on specific actionable genetic aberrations. Each subtype is associated with molecular tests that define the subtype and drugs that may potentially treat it. We hope this paper will be a useful guide to clinicians and researchers alike by assisting in therapy decision making and acting as a platform for further study. In this new era of cancer treatment, the 'one-size-fits-all' paradigm is being forcibly pushed aside-allowing for more effective, personalized oncologic care to emerge.

Figure 1. A major signaling pathway implicated in lung cancer is the EGFR pathway which signals to both the AKT/PI3K pathway (green) and the MAPK pathway (red) which regulate cell growth, proliferation and cell death.

There is significant cross-talk between these pathways and their downstream effectors, which we have classified into 6 pathways for simplicity to account for differences in treatment modalities. The additional 4 pathways are: EGFR (blue), KRAS (yellow), EML4-ALK (orange), and P53/BCL (purple). It is thought that the RAS/RAF/MEK/MAPK pathway may be constitutively activated by the EML4-ALK fusion oncogene . The complex relationship between this pathway and EML4-ALK is indicated with a dashed line.