Prognostic Factors in Lung Cancer

Lung cancer is a heterogeneous clinical entity of non-small-cell and small-cell lung cancer types as well as mixed types, with even different clinical behaviors and prognoses within particular pathological subgroups. Current guidelines for treatment decisions in NSCLC and SCLC are based on tumor extension and certain additional clinico-histophatological parameters only. Besides this, numerous clinical laboratory tests and investigations of the cellular, molecular and genetic biology of lung cancer and the environment have been introduced into routine in pathology, clinical chemistry and even nuclear medicine, describing the tumor better than ever before. This knowledge might support the treatment decision, research design and analysis, and may support the development of complex risk models for prediction of lung cancer mortality, and for the selection of an appropriate treatment for each individual case. Unfortunately, countless articles describing more than 150 different prognostic factors but with enormous heterogeneity by interstudy variations, patient selection bias, low number of patients in most trials, retrospective nature of the trials, and poor statistical power may cause confusion. The main purpose of this article with special focus on cancer related, patient related, and environmental aspects is to allow an impression on most important and significant prognostic factors, and to offer a basis for treatment decision in clinical practice concerning patients with small-cell and non-small-cell lung cancer. Most of those factors should not be taken into account for treatment selection, but to carefully use them for stratification in prospective clinical trials. It should always be kept in mind, that the development of new substances in medical oncology, and the improvements in both surgical and radiation oncology increase the therapeutic window, and will change the value of some of the mentioned prognostic factors in near future.