The predictive value of body protein for chemotherapy-induced toxicity

BACKGROUND. The use of body surface area in determining chemotherapy dosing , particularly in the obese, remains controversial. Total body nitrogen (TB N) measurement in patients with serious illness has been suggested to be an accurate predictor of clinical course. The ability of TBN to predict chemo therapy-induced neutropenia was examined in the current study. METHODS. TBN measurements were performed in 31 female outpatients with brea st carcinoma who were undergoing standard cyclophosphamide, methotrexate, a nd 5-fluorouracil (CMF)-based chemotherapy (median age, 48 years; range, 26 - 77 years). TEN was measured using the in vivo neutron capture analysis te chnique on Day 1 of Cycles 2-0. The chemotherapy toxicity index used was th e absolute neutrophil count nadir (ANCN). Neutropenia was defined as an ANC N < 1.0 x 10(9)/L. The nitrogen index (NI) (TBN expressed as a percentage o f age-, gender-. and height-matched healthy patients) then was compared wit h the cor responding ANCN values. RESULTS. Using receiver operating characteristics analysis, a "cut-off " va lue of NI = 0.89 was found. In this group of patients, when the NI was < 0. 89, 11 of 13 courses in 7 patients (85%) led to an ANCN of < 1.0 x 10(9)/L, and when the NI was > 0.89, 29 of 109 courses (27%) led to an ANCN of < 1. 0 x 10(9)/L (P < 0.0001). CONCLUSIONS. In this small group of breast carcinoma patients, the NI was f ound to be the most powerful predictor of neutropenia after CMF-based chemo therapy. The authors conclude that NI may be a useful clinical tool in iden tifying patients at a higher risk of chemotherapy-induced toxicity when wid ely distributed drug combinations such as CMF are used, and warrants furthe r study with other commonly used drugs or drug regimens. (C) 2000 American Cancer Society.