Challenges for the future modifications of the TNM staging system for head and neck cancer: case for a new computational model?

The TNM system of staging cancers is a simple and effective method to map the extent of tumours. It had traditionally strived to maintain a balance between being simple and user-friendly on one hand and comprehensive on the other. A number of revisions have taken place over the years with the goal of improving utility. However, numerous controversies surround the TNM system. There is a school of thought that contends that patient co-morbidity and specific tumour-related factors should be incorporated to add further prognostic capabilities in the TNM system, but this raises concerns that such an approach may unnecessarily complicate the system. This review highlights some controversies that surround the TNM system and suggests prognostic indicators that may be added to make it more useful in guiding treatment decisions and predicting outcomes.