Importance of weight loss definition in the prognostic evaluation of non-small-cell lung cancer.

In both clinical practice and scientific reporting, various definitions of weight loss (WL) are currently in use. A comparison of their efficiency would be appropriate. In this report, we describe the first clinical evaluation of different WL definitions. New consecutive non-small-cell lung cancer (NSCLC) patients (388) were prospectively studied at the Pulmonary Unit of 'S. Croce and Carle' Hospitals from 1995 to 1999. Multiple anthropometric, clinical and pathological data, along with eight WL-related variables, were analysed. Patients' length of survival was estimated using the Kaplan-Meier function and the Cox's multivariate regression. In univariate analysis, all WL variables were prognostically significant. Among them, total WL (i.e. the percent difference between the weight at diagnosis and the last weight recorded while in good health, dichotomised by the threshold level of 11%) was the most significant factor (Log-rank: 29.65, P=0.0000). The best Cox's model for survival prediction, constructed using all the available clinical information, included, in order of importance, the following three factors: stage of disease classification, performance status and total WL. Contrary to what one might expect, WL speedy was less predictive than WL quantity. Evidence from this study suggests that, while the loss of body weight is confirmed a significant prognostic factor in NSCLC, the value of this factor is partially dependent on its definition.