7th ICHNO Abstract book

page 66 7 th ICHNO Conference International Conference on innovative approaches in Head and Neck Oncology 14 – 16 March 2019 Barcelona, Spain __________________________________________________________________________________________ 7th ICHNO

Significant, but weak correlations were found between WL and higher D A to SMGs (r=0.32 for both), PCs (r=0.22 sup, r=0.36 mid) and SGL (r=0.33). No correlation between WL and higher D A to the PGs or OC was seen. Conclusion Delivered dose was higher than planned to all OARs, except oral cavity. Weight loss is weakly correlated with higher D A to some OARs. More advanced N-staging predicts higher D A to SMGs, PCs and SGL. Patients with nasopharyngeal primaries experience higher D A to the PGs, oral primaries result in higher D A to SPCs. These data can help guide ARTS, and may also be relevant for PBT, where anatomical change may lead to much greater dose differences. PO-127 How to optimize prophylactic lymph node irradiation in nasopharyngeal carcinoma? N. Fourati 1 , Z. Fessi 1 , W. Mnejja 1 , W. Siala 1 , J. Daoud 1 1 Hopital Habib Bourguiba, Radiation Oncology, Sfax, Tunisia Purpose or Objective The aim of this study is to evaluate the probability of node metastasis in nasopharyngeal carcinoma (NPC) to optimize the choice of prophylactic lymph node target volume. Material and Methods CT scan of 80 patients with pathologically confirmed NPC was retrospectively reviewed to determine sites of lymph node involvement according to the Radiation Therapy Oncology Group nodal classification guidelines (Gregoire 2013). All lymph nodes larger than 5 mm in the IA, Ib, II, III, IV, V and VIIb levels were selected. Level VIIa (retropharyngeal) was excluded from this study given the difficulties of differentiating between lymph node involvement and tumor invasion on CT imaging, especially for large tumors. The relationships between the different lymph node levels invasion was then studied.

Higher T-stage predicted higher D A for the OC (p=0.002, two-sample t-test), but not for other OARs. Higher N-stage predicted higher D A to SMGs, PCs and SGL (all p values < 0.0005), but not OC or PGs. The most striking relationships between PDS and higher OAR D A were PGs for nasopharynx, and SPCs for oral cavity (Figure 2).