Increased understanding of the biology of cancer, its initiation, growth, and progression, has provided a basis for experimental therapies that seek clinical application of the basic research information. We anticipate that new markers of prognosis will be identified and confirmed from the research, as well as reproducible, cost-effective methodologies. However, until this work becomes a reliable and proven clinical reality, anatomic and morphologic classifications remain as a benchmark for measuring prognosis.

In presenting the revised staging recommendations, we recognize that in a given patient the total tumor burden cannot be precisely quantitated, and the balance between host defenses and the heterogeneity of the malignancy is not measurable. These and other complex interacting biological variables will influence the subsequent course of the disease. However, our data support the premise that the straightforward indices of disease extent in the TNM system permit a simple yet valid classification that best reflects prognosis. Patients can be grouped together according to certain measurable common features of their disease so that within each stage group, treatment options and survival expectations will be generally similar. In this manner, reliable and valid comparisons of the results of different modalities of therapy can be made. Survival data presented according to staging criteria are a measure of the efficacy of available therapy for lung cancer; thus, the staging information serves as a valuable guide for treatment planning.