lung_cancer_staging/staging/tnm_classification?

TNM Classification

The American Joint Committee on Cancer (AJCC) as well as the International Union Against Cancer (UICC) recommend TNM staging, which is a two step procedure. Their TNM system, which they now develop jointly, first classifies cancer by several factors, T for tumor, N for nodes, M for metastasis, and then groups these TNM factors into overall stages as shown in their table.

AJCC has provided web accessible poster versions of these copyrighted TNM descriptors and stage groups, to which readers are directed for accurate, detailed, up to date information; additionally, both the National Cancer Institute (NCI) and the National Comprehensive Cancer Network (NCCN) reprint these descriptors and grouping tables with AJCC permission, and extensively discuss staging modalities and treatment options, providing expert clear assistance in decisions about the best treatments. The NCCN pathways "outline the step-by-step treatment decisions from diagnosis through all phases of treatment and survivorship."

Although TNM classification is an internationally agreed system, it has gradually evolved through its different editions; the dates of publication and of adoption for use of AJCC editions is summarized in the table in this article; past editions are available from AJCC for web download. Therefore, it is important when reviewing reports of treatment or prognosis to be aware that the criteria used in the TNM system have varied over time, sometimes fairly substantially, according to the different editions. Literature reports usually reflect the staging that was in use while the study was initiated and performed, rather than when it was eventually published. The dates of publication and adoption for use of AJCC editions is summarized here to assist readers in understanding which era is being used by the literature.

As in each edition of the TNM staging system, that used from 2010 January 1 (7 edition) made significant changes to the schema that is used for non-small cell lung carcinoma, small-cell lung carcinoma and broncho-pulmonarycarcinoid tumors. The revisions were based on a detailed analysis and consensus process by AJCC and UICC that looked at the overall survival of 81,015 patients. The changes have been reviewed in detail, including an extensive presentation (with multiple tables and detailed discussion) of prognostic data for both 6th and 7th edition, looking at both individual T, N and M descriptors, and at overall stage groups. The table uses limited excerpts from the copyrighted TNM system to demonstrate the concept that there are changes, as well as similarilities, between editions.

As a result, a given stage may have quite a different prognosis depending on which staging edition is used, independent of any changes in diagnostic methods or treatments, an effect that has been termed "stage migration." The technologies used to assign patients to particular categories have changed also, and it can be seen that increasingly sensitive methods tend to cause individual cancers to be reassigned to higher stages, making it improper to compare that cancer's prognosis to the historical expectations for that stage.

Finally, of course, a further important consideration is the effect of improving treatments over time as well.

Of considerable historical importance, Dr. Clifton Mountain, a surgeon in Texas, made significant contributions to the TNM staging system, particularly in non-small cell lung carcinoma, and the literature thus often refers to "Mountain" staging.