Comparative Study of Dysphagia-optimized Intensity Modulated Radiotherapy (Do-IMRT) and Standard Intensity Modulated Radiotherapy (S-IMRT) and Its Clinical Correlation in Head and Neck Cancer Patients.

OBJECTIVE: Dosimetric sparing of critical swallowing structures like constrictor muscles and larynx can lead to improved functional outcomes in head and neck cancer patients treated by chemoradiation. METHODS: A total of 50 Patients with newly diagnosed, biopsy proven AJCC stage II-IV head and neck squamous cell cancers (HNSCC) were prospectively studied. 25 patients were randomized in each arm of Dysphagia-optimized Intensity Modulated Radiotherapy (Do-IMRT) arm and Standard Intensity Modulated Radiotherapy (SIMRT) arm. Additional dose constraints were applied to the dysphagia/aspiration at risk structures (DARS) in Do-IMRT arm. The impact of using Do-IMRT was assessed by the difference in mean scores of MD Anderson Dysphagia Inventory (MDADI), University of Washington-Quality of Life (UW-QOL), and 100 ml Water Swallow Test (WST). RESULTS: Patients in both arms showed significant (P <0.01 or P < 0.001) improvement in MDADI (global and composite), UW-QOL and Water Swallow Test scores. However, the improvements were found significantly higher in Do-IMRT as compared to S-IMRT. Significant improvements i.e. mean change from baseline to 12 months (P <0.05 or P <0.01 or P <0.001) were 19. 2, 8.6, 14.3, 7.4, 18.6 and 22.0%  higher respectively in Do-IMRT as compared to S-IMRT  in MDADI global and composite scores, UW-QOL swallowing scores, and 100 ml Water Swallow  (swallowing volume, swallowing capacity and swallowing speed)  test scores. CONCLUSION: The Do-IMRT improves swallowing functions compared to S-IMRT in HNSCC patients treated with radical chemoradiation.

A Study to Assess the Dosimetric Impact of the Anatomical Changes Occurring in the Parotid Glands and Tumour Volume during Intensity Modulated Radiotherapy using Simultaneous Integrated Boost (IMRT-SIB) in Head and Neck Squamous Cell Cancers.

BACKGROUND: Anatomical variations in head and neck cancer during IMRT leads to volume shrinkage, results in dosimetric variations in tumour and normal tissue including parotid glands, with a risk of radiation toxicities. METHODS: 30 patients with a stage II-IV head and neck squamous cell carcinoma (HNSCC) were treated with definitive IMRT-SIB and concomitant chemotherapy. Volumetric and dosimetric variations were evaluated during the period of IMRT by recalculating and obtaining dose-volume histograms of re-contoured target volumes and parotid glands on repeat CT scans taken multiple times during treatment (CT1, CT2, CT3 and CT4). RESULTS: Result showed significant (p < 0.001) mean decrease in both primary and nodal tumors volume with time whereas increase (p < 0.01 or p < 0.001) in respective V100 (%) and D2% (Gy). The mean parotid gland dose increased (p < 0.01 or p < 0.001) with time, whereas parotid gland volume and distance between plan isocenter and centre of mass of parotid glands decreased (p < 0.05 or p < 0.001) with time. Patient's mean weight and neck circumference both decrease (p < 0.001) with time whereas ECOG score increase (p < 0.001) with time. The mucosal toxicity increased significantly (p < 0.001) with time. The change in both weight and neck circumference showed significant (p < 0.001) and direct (positive correlation) association with change in parotid gland volume. CONCLUSION: If the PTV and normal anatomy are changing with time, adaptive IMRT would be beneficial radiation dose delivery where possible.