ESTRO 2021 Abstract Book

S814

ESTRO 2021

Conclusion RDT discrimination power is probably influenced by treatment characteristics of clinical cohorts (RT setting/doses, association of CHT). This underlines the importance of combining RDT with treatment/dosimetric features (AUCs largely improved for the combined models) for predicting tox. Due to our study results, implementing RTD as an easy managing test in common RT clinical practice for HNC patients is advisable. PO-0981 Wide histological spectrum of sinonasal malignancies and survival outcomes - An Institutional review P. Umesh 1 , S. Tandon 2 , M. Gairola 2 , P. Ahlawat 2 , S. Purohit 2 , K. Dobriyal 2 1 Rajiv Gandhi Cancer Institute and Research Centre, Radiation Oncology, New Delhi, India; 2 Rajiv Gandhi Cancer Institute and Research Centre, Radiation Oncology, Delhi, India Purpose or Objective With recent advancements in our diagnostic capabilities, the range of histologies observed in sinonasal malignancies have increased manifolds. Elaborate immunohistochemistry and detailed microscopic examination have diversified our diagnosis which were initially labelled as “poorly differentiated malignancy”. This review aims at understanding the different histologies observed over the past decade, their treatments The institutional database was reviewed from January 2010 - December 2020, 258 patients with sinonasal malignancy were identified. Sixty-two patients defaulted to treatment after their initial diagnosis. Analysis was calculated for 196 patients for whom data-sets were complete. Survival-analysis with endpoints of overall survival (OS) and loco-regional free survival (LRFS) was done. Results The majority patients were male (65.8%) with tumours primarily located in the maxillary sinus (34.7%) and the nasal cavity (41.3%). Most of the patients presented with obstructive symptoms (34.2%) and subsequent epistaxis (27%) and mass effect (27.5%). The analysis reinforced the incidence of multiple histologies in the paranasal location. Squamous cell carcinoma (SqCC) (39.8%) was the most common histology followed by small cell carcinoma (SCC) (15.3%) and adenoid cystic carcinoma (ACC) (11.2%). The median OS for SqCC and ACC was not reached. The median OS for SCC was 24.0±3.9 (range 16.3 -31.6) months. The median LRFS for SqCC and adenocarcinoma was 52.0±12.5 (range 27.3 – 76.6) months and 50.0±19.3 (range 12.0 – 87.9) months, respectively. Tumours located in maxillary sinus did fairly better with median OS and LRFS, 135.0±49.7 (range 37.3 – 232.6) months and 73.0±13.3 (range 46.7 – 99.2) months, respectively. Patients who had surgery incorporated in their treatment protocol did better (median OS 66.0±14.5 (range 37.5 – 94.4) months vs 46.1±12.7 (range 16.0 – 65.9) months). and survival outcomes. Materials and Methods