ESTRO 2021 Abstract Book

S806

ESTRO 2021

"Optimal threshold cut-off value of Hb level" for which there was greatest difference in survival. AUC, sensitivity and specificity were also calculated to analyze the predictive ability of this cut off. The results showed that Hb level ≥ 13.5 g/dl predicted the survival with a sensitivity of 75.4 %, specificity of 53.5 % and with an AUC of 0.632 (95% CI, 0.518 - 0.747; p = 0.024). There was greatest magnitude of difference in early outcome in patients having Hb level above and below this level of 13.5 g/dl. There was statistically improved LRFS between patients having Hb ≤ 13.5 g/dl and > 13.5 g/dl ( p = 0.001 ). Patients with Hb ≤ 13.5 g/dl had a median LRFS of 8 months (4.2 – 11.8 months), patients with Hb > 13.5 g/dl had not achieved their median LRFS. There was a statistical improved OS between patients having Hb ≤ 13.5 g/dl and > 13.5 g/dl ( p = 0.003 ). Patients with Hb ≤ 13.5 g/dl had a median OS of 25 months (18.2 – 31.8 months), patients with Hb > 13.5 g/dl had not achieved their median OS.

Conclusion Low baseline Hb (less than 13.5 g/dl in our study) is poor prognostic marker for survival in HNC patients treated with definitive RT.

PO-0973 Locoregional treatment of primary tumor in synchronous metastatic HNSCC: A retrospective study E. Tang 1 , T. Nguyen 2 , N. Haddy 3 , B. Schwartz 3 , C. Even 4 , P. Blanchard 2 , P. Gorphe 5 , Y. Tao 2 , F. Ferrand 4 1 Gustave Roussy, Radiation Oncology , Villejuif, France; 2 Gustave Roussy, Radiation Oncology, Villejuif, France; 3 Gustave Roussy, Radiation Epidemiology, Unité 1018 INSERM, Villejuif, France; 4 Gustave Roussy, Head and Neck Oncology, Villejuif, France; 5 Gustave Roussy, Head and Neck Surgery, Villejuif, France Purpose or Objective Patients with synchronous metastatic head and neck squamous cell carcinomas (mHNSCC) are at risk of locoregional progression associated with significant morbi-mortality. The aim of this study is to assess the role of locoregional treatment directed to primary tumor when associated with systemic therapy as first-line treatment. Materials and Methods