A System for the Clinical Staging of Lung Cancer

S TAGING of neoplastic disease is the procedure of assigning a simple coded designator to a patient in accordance with an established set of rules. Its purpose is to classify patients and group them with respect to the anatomic extent or biologic severity of their disease. Clinical staging is based only on those measures of disease extent which are available from diagnostic or evaluative studies undertaken prior to instituting therapy. This classification of patients into relatively homogeneous groups, with respect to estimates of their prognosis, is essential if different modalities of treatment are to be compared and if results are to be communicated in meaningful terms. The central problems in designing a meaningful staging system are: (I) to identify and give proportionate weight to those factors which will reliably and validly predict survival; and (2) to develop rules which, when applied to these factors, will permit assignment of an index of disease extent. The essential character of such an index is that patients within any stagegroup who survive equivalent treatment will demonstrate a generally similar ageadjusted life expectancy. A major constraint on any system of classifying the extent of disease is that it must be easily understood and remembered; therefore, it must be based on relatively few predicting factors. Only a relatively uncomplicated system will lend itself to widespread utilization. Among the systems of classification proposed by international organizations and 8 10, 14, 17 and mdi viduals6 are classification schemes applicable speci f-icalby to lung cancer.”2 Some of these have been found wanting,5’9”3 and none have achieved wide acceptance to date. The TNM classification scheme, first proposed by Denoix,4 meets many of the criteria and constraints noted above, and its principles are well established internationally.’6 Therefore, the general rules of the TNM system were adopted in this investigation, undertaken under the auspices of the Task Force