Dissociation of body weight and lean body mass during cancer chemotherapy

Body weight and lean body mass are different reflections of the nutritional status of patients receiving cancer chemotherapy. In the present study, the relation between lean body mass and body weight during cytostatic treatment was investigated in 3 groups of newly-diagnosed children and young adults with acute lymphocytic leukemia, osteosarcoma, or a small round cell sarcoma. Body weight and lean body mass were determined before and after an initial period of cytostatic treatment. Lean body mass was derived from total body water volume, which was assessed by deuterium oxide dilution. A significant dissociation between body weight and lean body mass was observed in leukemia patients (n = 8, P = 0.008, paired t-test), and in osteosarcoma patients (n = 13, P = 0.001). No dissociation was found in patients with a small round cell sarcoma (n = 8, P = 0.839). We conclude that during cancer chemotherapy periodic assessment of body weight may give a false picture of the preservation of lean body mass. Considering the course of body weight alone may prevent the establishment of a timely diagnosis of malnutrition, which is mandatory for optimal supportive care.