Abstract and Introduction
Abstract
The 7th edition of TNM for Lung Cancer represented a major advance from previous editions, in the process of revision, the size and breadth of the data base used, its international character, the intensity of the analysis and the critical nature of the internal and external validation undertaken before its launch in January 2010. This all came about by the involvement of the International Association for the Study of Lung Cancer (IASLC), which assumed the role previously performed by Dr. Mountain, of developing data-driven revisions for the Union for International Cancer Control (UICC) and the American Joint Committee on Cancer (AJCC). In taking on this task the IASLC made the global lung cancer community aware of the limitations of previous revisions and now stand accountable and subject to the same scrutiny. In this article we describe the achievements of the IASLC TNM and Prognostic Factors Committee, but also the short-comings of the 7th edition, as an essential step towards rectifying deficiencies and further improving the classification in future revisions.
Introduction
To properly understand the achievements of the 7th edition of TNM for Lung Cancer it is necessary to give a brief history of the TNM Classification itself. A more detailed history of this topic is available elsewhere.
A system to describe the anatomical extent of a cancer using the "T", "N" and "M" descriptors was developed by Dr. Pierre Denoix, a surgical oncologist at the Institut Gustave-Roussy in Paris, and evolved over a series of articles in the 1940s and early 50s. The first international classification of malignant disease based on TNM was published in 1968 by the Union Internationale Contre le Cancer (UICC), which now prefers to be known by the English version of its title, Union for International Cancer Control, lung cancer being included under the section for "other sites". This initial attempt at classification was arrived at by discussion and consensus, there being no data available. The American Joint Committee for Cancer Staging and End Results Reporting, now the American Joint Committee on Cancer (AJCC), orchestrated the collection of data through its Task Force on Lung Cancer. The analysis of a data base of 2,155 lung cancer cases resulted in "A system for the clinical staging of lung cancer" reported by Drs. Mountain, Carr and Anderson in 1973. This formed the basis of the 2nd edition of the UICC TNM Classification of Malignant Disease published in 1975 and the 1st edition of the AJCC Manual for Cancer Staging published in 1977. Thereafter Dr. Mountain developed his own data base which informed future revisions up to and including the 5th edition published in 1997, by which time the data base had accumulated 5,319 cases. There were no changes in the lung cancer classification in the 6th edition.
At a workshop sponsored by the International Association for the Study of Lung Cancer (IASLC) and held at the Brompton Hospital in London in 1996 Dr. Mountain presented his revisions for the 5th edition of TNM which had been approved by the UICC and AJCC and were due to come into force within a few weeks. The deficiencies of the underlying data were discussed: a relatively small number of cases, accumulated over 20 years, predominantly cases referred for surgical consideration and mostly derived from a single institution. The workshop attendees recommended "the establishment by the IASLC of a staging committee" to "represent the IASLC in negotiations with UICC and AJCC with regard to future revisions of classification".