[Impact of reconstructive or minimal invasive surgery on the assessment of current definitions of postoperative clinical target volume for head and neck cancers]. / Impact de la chirurgie reconstructrice avec lambeaux et de la chirurgie mini-invasive sur la définition du volume cible anatomoclinique des cancers de la sphère ORL.

Advances in the reconstructive surgery and minimally invasive endonasal endoscopic surgery of head and neck is poorly evaluated in terms of their impact on radiotherapy planning and outcomes. These surgical advances have resulted in reduced morbidity with equivalent or better tumor control. In the absence of a recommendation on how to delineate target volumes in patients with flaps or to consider margins after endoscopic endonasal surgery, radiotherapy practices are inevitably heterogeneous. Efforts are needed to increase the therapeutic index of postoperative radiotherapy in these situations. We analysed the rare existing literature and outlined a preliminary basis for a recommendation. Strengthening of multidisciplinarity to accurately define target volumes in these complex and relatively new situations, and "delineation concertation meetings" between radiologists, surgeons and radiation oncologists could probably contribute to improved outcomes.

[Intensity modulated radiotherapy for head and neck cancer, dose constraint for normal tissue: Cochlea vestibular apparatus and brainstem]. / Radiothérapie conformationnelle avec modulation d'intensité des cancers des voies aérodigestives supérieures, dose de tolérance des tissus sains : appareil cochléovestibulaire et tronc cérébral.

Modern techniques such as intensity modulated radiation therapy (IMRT) have been proven to significantly decrease the dose delivered to the cochleovestibular apparatus, limiting consecutive toxicity especially for sensorineural hearing loss. However, recent data still report a 42% rate of radio-induced hypoacusia underscoring the need to protect the cochleovestibular apparatus. Due to the small size of the cochlea, a precise dose-volume analysis could not be performed, and recommendations only refer to the mean dose. Confusing factors such as age, concomitant chemotherapy, primary site and tumor stage should be taken into account at the time of treatment planning. (Non-coplanar) VMAT and tomotherapy have been proven better at sparing the cochlea in comparison with 3D CRT. Brainstem radio-induced injuries were poorly studied because of their infrequency and the difficulty of distinguishing between necrosis and tumor progression in the case of a primary tumor located at the base of skull. The following toxicities have been described: brainstem focal radionecrosis, cognitive disorders without dementia, cranial nerve injuries and sensori motor disability. Maximal dose to the brainstem should be kept to < 54Gy for conventional fractionation. This dose could be exceeded (no more than 10mL should receive more than 59Gy), provided this hot spot is located in the peripheral area of the organ.

Poster - Thur Eve - 73: Prediction of risks of cardiac mortality and secondary cancers after radiotherapy for Hodgkin's lymphoma, non-Hodgkin's lymphoma, and breast cancer.

PURPOSE: To predict the risks of late, radiation-induced effects for young patients with Hodgkin's lymphoma (HL), non-Hodgkin's lymphoma (NHL), or breast cancer (BC) if treated with intensity modulated proton therapy (IMPT) compared to 3D conformal photon radiotherapy (3D-CRT). Late effects considered were cardiac mortality and secondary cancer in the lungs and breasts (for female patients). METHODS: Patient data were acquired for twenty-six patients (ages 12-29) who were treated with 3D-CRT for HL, NHL, or BC in 2010. Original CT simulation images were used to re-plan the patients with IMPT using commercially-available treatment planning software. The contours of the organs at risk were reviewed by a single physician and modified for consistency. The dose-volume data of the 3D-CRT plans and the new IMPT plans were analyzed to model the risks of late effects. The relative seriality model was used to predict excess risk of cardiac mortality at fifteen years post-irradiation. A modified linear quadratic model was used to predict the Excess Absolute Risk (EAR) for induction of lung cancer and breast cancer at thirty years post-irradiation. RESULTS: For 3D-CRT and IMPT respectively, the mean excess risks of cardiac mortality were 0.9% and 0.5%. Mean EARs for lung cancer were 17.5 cases per 10,000 persons per year (PY) and 10.1 PY. Mean EARs for breast cancer were 8.2 PY and 2.8 PY. CONCLUSIONS: IMPT may significantly reduce the risks of radiation-induced cardiac mortality and secondary cancer in the lungs and breasts of young patients receiving radiotherapy for HL, NHL, or breast cancer.