This study compared the resting energy expenditure (REE) modifications observed during successive intensive identical chemotherapy courses in non-Hodgkin's lymphoma patients to assess indirectly the metabolic changes induced by the cytotoxic effect of drugs on the tumor. With this therapeutic regimen, reduction of tumor mass is mostly achieved during the first course of chemotherapy. The study included 10 non-Hodgkin's lymphoma adult patients receiving three intensive 5-day courses of Adriamycin (doxorubicin; Adria Laboratories, Columbus, OH), cyclophosphamide, vindesine, and bleomycin. Resting energy expenditure was evaluated by indirect calorimetry during each course, first within the first 2 days before chemotherapy and then on days 2, 3 and 5. Initial REE (day 0) on entry into the study (21.8 +/- 1.2 kcal/kg.d-1) represented 99 +/- 6.7% of theoretical REE. Resting energy expenditure on day 0 was lower during course 2 and 3 (19.1 +/- 0.7 and 18.4 +/- 1.8 kcal/kg/d) than during course 1 (21.8 +/- 1.2 kcal/kg/d). The REE profile was different among the 3 courses: course 1 induced a significant REE decrease on days 3 and 5 (P less than 0.01); during course 2, REE remained stable and was lower than during course 1; during course 3, REE increased on days 2, 3, and 5 (P less than 0.05). Energy balance was positive during the three courses and nutritional status remained stable. The REE decrease observed during course 1 may be regarded as the metabolic effect of chemotherapy on the tumor metabolism.