Effects of Treatment Strategies and Demographic Characteristics on Normal Tissue Complication Probability in Head and Neck Radiotherapy Using the Lyman Model

This study aimed to evaluate the effects of treatment strategies and patient's demographics characteristics on normal tissue complication probability in head and neck radiotherapy using the Lyman model. 78 patients with head and neck cancers who had finished their period of treatment in the last three years were investigated. The available information in the CorePlan treatment Planning system for each patient was gathered. Finally, the normal tissue complication probability (NTCP) was determined from the dose received to the target volume and the irradiated volume using statistical model used in the CorePlan treatment planning system (Lyman model). In this work, descriptive statistics such as mean and proportion was applied to describe the data and Mann-Whitney, Kruskal-Wallis, and Spearman correlation-coefficient test also were employed. The normal tissue complication probability was found to be strongly influenced by the position of normal tissues to radiation. In addition, a significant relationship was observed between the tumor and its adjacent normal tissues (P < 0.050). Complication risk of thyroid and dose increasement was significantly correlated (P = 0.004). There was no significant relationship between the age group, sex, stage of tumor, treatment type and normal tissue complication probability (P > 0.050). According to our findings, there was a significant relationship between the tumor location and the normal tissue complication probability. Thus, optimization of treatment planning system and use of appropriate equipment are useful in improving the symptoms of head and neck cancer after radiotherapy. Using high-dose radiation for head and neck cancers should be evaluated to protect thyroid, especially when the tumor is in the neck.