Quantitative body mass characterization before and after head and neck cancer radiotherapy: A challenge of height-weight formulae using computed tomography measurement

Objectives We undertook a challenge to determine if one or more height-weight formula(e) can be clinically used as a surrogate for direct CT-based imaging assessment of body composition before and after radiotherapy for head and neck cancer (HNC) patients, who are at risk for cancer- and therapy-associated cachexia/sarcopenia. Materials and methods This retrospective single-institution study included 215 HNC patients, treated with curative radiotherapy between 2003 and 2013. Height/weight measures were tabulated. Skeletal muscle mass was contoured on pre- and post-treatment CT at the L3 vertebral level. Three common lean body mass (LBM) formulae (Hume, Boer, and James) were calculated, and compared to CT assessment at each time point. Results 156 patients (73%) had tumors arising in the oropharynx and 130 (61%) received concurrent chemotherapy. Mean pretreatment body mass index (BMI) was 28.5 ± 4.9 kg/m² in men and 27.8 ± 8 kg/m² in women. Mean post-treatment BMI were 26.2 ± 4.4 kg/m² in men, 26 ± 7.5 kg/m² in women. Mean CT-derived LBM decreased from 55.2 ± 11.8 kg pre-therapy to 49.27 ± 9.84 kg post-radiation. Methods comparison revealed 95% limit of agreement of ±12.5–13.2 kg between CT and height-weight formulae. Post-treatment LBM with the three formulae was significantly different from CT (p < 0.0001). In all instances, no height-weight formula was practically equivalent to CT within ± 5 kg. Conclusion Formulae cannot accurately substitute for direct quantitative imaging LBM measurements. We therefore recommend CT-based LBM assessment as a routine practice of head and neck cancer patient body composition.