Delineation of neck node levels for patients with locally advanced supraglottic cancer receiving radical intensity-modulated radiotherapy: a cross-sectional study in Mainland China

Background: To survey the diversity of clinical target volumes (CTVs) for locally advanced supraglottic cancer (LA-SGC) with radical radiotherapy in mainland China. Methods: Radiation oncologists from 30 provinces and four representative cases (T2N1, T3N2b, T4N0, T4N2c) were included. Results: High risk (HR)-CTV included involved and the lower adjacent level was followed by most physicians (n = 160, 97.6%). In the N0-1 stage, whether contralateral levels II-III should be included in HR- or low risk (LR)-CTV was controversial. In the N2 stage, the bilateral levels II-IVb were included in LR-CTV (75-92.5% agreement). Levels Ib, V or VIb were included in CTV requiring certain conditions. Conclusion: Involved and lower adjacent levels were as HR-CTV. Whether bilateral levels II-IV are included in HR- or LR-CTV remain controversial.