Taxane-containing induction chemotherapy followed by definitive chemoradiotherapy. Outcome in patients with locally advanced head and neck cancer.

BACKGROUND: Induction chemotherapy followed by definitive chemoradiotherapy is an intensified treatment approach for locally advanced squamous cell carcinoma of the head and neck (HNSCC) that might be associated with high rates of toxicity. MATERIALS AND METHODS: The data of 40 consecutive patients who underwent induction chemotherapy with docetaxel-containing regimens followed by intensity-modulated radiotherapy (IMRT) and concomitant systemic therapy for unresectable locally advanced HNSCC were retrospectively analyzed. Primary objectives were RT-related acute and late toxicity. Secondary objectives were response to induction chemotherapy, locoregional recurrence-free survival (LRRFS), overall survival (OS), and influencing factors for LRRFS and OS. RESULTS: The median follow-up for surviving patients was 21 months (range, 2-53 months). Patients received a median of three cycles of induction chemotherapy followed by IMRT to 72 Gy. Three patients died during induction chemotherapy and one during chemoradiotherapy. Acute RT-related toxicity was of grade 3 and 4 in 72 and 3 % of patients, respectively, mainly dysphagia and dermatitis. Late RT-related toxicity was mainly xerostomia and bone/cartilage necrosis and was of grade 3 and 4 in 15 % of patients. One- and 2-year LRRFS and OS were 72 and 49 % and 77 and 71 %, respectively. CONCLUSION: Induction chemotherapy followed by chemoradiotherapy using IMRT was associated with a high rate of severe acute and late RT-related toxicities in this selected patient cohort. Four patients were lost because of fatal complications. Induction chemotherapy did not compromise the delivery of full-dose RT; however, the use of three cycles of concomitant cisplatin was impaired.

SU-E-T-507: Dose Calculation Quality of AcurosXB Involving a HD120 MLC Compared with Monte Carlo Methods.

PURPOSE: Advanced radiation therapy requires highly sophisticated dose calculation algorithms such as finite element based Boltzmann solvers or Monte Carlo (MC) methods. MC is commonly accepted as the golden standard method for dose calculation in high energy treatments and thus it is used for benchmarking other algorithms. In this work the quality of dose distribution calculated using the Boltzmann solver based AcurosXB algorithm within Eclipse (Varian Medical Systems) is investigated for volumetric modulated arc treatment (VMAT) plans involving the high definition MLC (HD120 MLC) by comparing doses with the validated Swiss Monte Carlo Plan (SMCP). MATERIALS & METHODS: Within SMCP and Eclipse using AcurosXB, 10 VMAT H&N patient plans and corresponding verification plans were recalculated using fixed MUs. In SMCP, radiation transport and dose calculation were performed using VMC++ with a statistical uncertainty of 1%. The voxel size was 2.5 mm for SMCP and AcurosXB and the same material composition data was used for CT conversion. Dose volume histograms (DVH) were used in order to quantify the difference between the dose distributions of the patient plans. In addition, calculated verification plans were compared with measurements carried out with the Delta4 system (Scandidos) by using the gamma evaluation with 3%/3 mm criteria of points having a dose larger than 20% of isocenter dose. RESULTS: DVHs for the patient plans showed good agreement between SMCP and AcurosXB calculations. Overall AcurosXB lead to an underestimation of the median dose values by about 1%. For measured total dose distributions of the verification plans on average 98.6% and 99.0% of the points fullfil the gamma criteria for the dose calculated using AcurosXB and SMCP, respectively. CONCLUSIONS: Resulting AcurosXB dose distributions for VMAT H&N plans involving a HD120 MLC are in good agreement with calculated SMCP dose distributions. CONFLICT OF INTEREST: This work was supported by Varian Medical Systems.