Prognostic factors for small-cell lung cancer

Knowledge of the factors that predict the clinical outcome of a patient with small-cell lung cancer (SCLC) is critical to guiding treatment and to determining prognosis. The benefit of defining these prognostic factors, however, goes well beyond the individual patient. In 1973 the Veterans' Administration Lung Study Group (VALSG) [1] described a staging system for SCLC that divided patients into localized disease or extensive disease based upon the ability to administer radiotherapy. With the advent of this staging system, the treatment of patients with SCLC began to become standardized across institutions. This type of classification into different prognostic groups facilitated the planning and interpretation of results of clinical trials. In turn, these trials have allowed the collection of additional data that has ultimately led to a better understanding of additional factors that predict for significant patient outcomes including response to therapy, duration of response, and survival. This better understanding further refines clinical trials and ultimately leads to improved care for all patients with SCLC. In the pages that follow, we will examine the factors that have been investigated for their prognostic significance and bring perspective to the power each factor has in determining the ultimate outcomes of patients.