Discussion
dysphagia, tumor, squamous cell HNC, long-term swallowing complications, malnutrition
DYSPHAGIA, TUMOR, MALNUTRITION, REGRESSION, COMPLICATIONS
Overall, this prospective nutritional intervention study identified icm V40Gy (%) as a relevant parameter predictive of malnutrition at the end of RT or combined CRT. Regardless of our intensive literature research, we did not detect any publications relating doses to the swallowing apparatus to malnutrition (as defined by BIA). Therefore, we extended our research to an indirect surrogate parameter of malnutrition, namely known dysphagia or other swallowing complications.To identify dosimetric predictors of long-term swallowing complications, Caudell et al. investigated 83 patients undergoing definitive RT due to squamous cell HNC [Besides the glottic and supraglottic larynx and esophagus, Feng et al. proposed the pharyngeal constrictors to be associated with swallowing complications when mean doses of > 60 Gy or a volume receiving 65 Gy of more than 50% were exceeded [The main limitation of this analysis is its small sample size, which implies a reduced power to detect small effects. To avoid model overfitting, four separate multivariable logistic regression models were built. At the same time, it cannot be determined to what extent the variables would have influenced each other across models. However, it must be emphasized that not only dosimetric factors exist that influence subsequent malnutrition, but that also diverse clinical variables may have an impact. To avoid model overfitting, we tested only four additional variables (combined chemotherapy, gender, malnutrition at baseline, and tumor location). Certainly, the question of the use of an inlying gastrostomy tube under ongoing RT could also have been an interesting parameter. Since, in our experience, it cannot automatically be assumed that patients regularly used the feeding tube despite its insertion, we decided not to include this parameter. Furthermore, the variables tested here represent only a selection of possible influencing variables.The initial study design included two study groups, namely an intervention group and a control group. However, it has already been shown in our previously published work [In conclusion, malnutrition at the end of therapy was strongly associated with malnutrition at baseline and the dose exposure to icm V40Gy (%), emphasizing the need to maintain a good nutritional status even before RT start and to undercut corresponding dose constraints.Plot of ROC analysis for icmV40Gy (%) indicating the 95% interval (