Swallowing-sparing intensity-modulated radiotherapy for head and neck cancer patients: treatment planning optimization and clinical introduction.

To report on the potential benefits of swallowing-sparing intensity-modulated radiation therapy (SW-IMRT) in the first 100 SW-IMRT treated patients, as well as on the factors that influence the potential benefit of SW-IMRT relative to standard parotid sparing (ST)-IMRT. One hundred consecutive head and neck cancer patients, scheduled for primary radiotherapy, were included in this prospective cohort study. For each patient, ST-IMRT and SW-IMRT treatment plans were created. All patients were eventually treated with SW-IMRT. Objectives for SW-IMRT were identical to those with ST-IMRT, with additional objectives to spare the swallowing organs at risk (SWOARs). After 20 patients, interim results were evaluated by a multidisciplinary committee. The mean gain of SW-IMRT relative to ST-IMRT in the first 20 patients was less than expected based on our previous planning comparative study. A critical review of all plans revealed that the results with SW-IMRT could be improved by: (1) gaining experience and attempting to reduce SWOAR dose as much as possible; (2) accepting a moderate shift of dose to unspecified tissues; (3) maximizing SWOAR sparing while keeping PTV coverage exactly according to protocol. In the additional 80 patients, the mean dose to the various SWOARs was further reduced significantly compared to ST-IMRT. Dose reductions with SW-IMRT were largest for patients who received neck irradiation, had a tumour located in the larynx, oropharynx, nasopharynx or oral cavity, and had <75% overlap between SWOARs and PTVs. The mean absolute reduction in predicted physician-rated RTOG grade 2-4 swallowing dysfunction for patients numbered 21-100 was 6.1%, ranging from 0.0% to 17.2%. The benefit of SW-IMRT depends significantly on neck radiotherapy, tumour site and the amount of overlap between SWOARs and PTVs. Optimal clinical introduction requires a detailed evaluation and comparison between the standard (ST-IMRT) and new technique (SW-IMRT) in order to fully exploit the potential benefits.

van der Laan HP ，Gawryszuk A ，Christianen ME ，Steenbakkers RJ ，Korevaar EW ，Chouvalova O ，Wopken K ，Bijl HP ，Langendijk JA ... -  《-》

The potential of intensity-modulated proton radiotherapy to reduce swallowing dysfunction in the treatment of head and neck cancer: A planning comparative study.

van der Laan HP ，van de Water TA ，van Herpt HE ，Christianen ME ，Bijl HP ，Korevaar EW ，Rasch CR ，van 't Veld AA ，van der Schaaf A ，Schilstra C ，Langendijk JA ，Rococo cooperative group ... -  《-》

The potential benefit of swallowing sparing intensity modulated radiotherapy to reduce swallowing dysfunction: an in silico planning comparative study.

To apply recently developed predictive models for swallowing dysfunction to compare the predicted probabilities of swallowing dysfunction for standard intensity modulated radiotherapy (ST-IMRT) and swallowing sparing IMRT (SW-IMRT). Thirty head and neck cancer patients who previously underwent radiotherapy for the bilateral neck were selected for this study. For each patient, ST-IMRT and SW-IMRT simultaneous integrated boost treatment plans were created. ST-IMRT treatment plan optimisation aimed at obtaining adequate target volume coverage and sparing of the parotid and submandibular glands as much as possible. Objectives for SW-IMRT were similar, with additional objectives to spare the organs at risk related to swallowing dysfunction (SWOARs). Dose-volume data with ST-IMRT and SW-IMRT and normal tissue complication probabilities for physician-rated and patient-rated swallowing dysfunction were calculated with recently developed predictive models. All plans had adequate target volume coverage and dose to critical organs was within accepted limits. Sparing of parotid glands was similar for ST-IMRT and SW-IMRT. With SW-IMRT, the mean dose to the various SWOARs was reduced. Absolute dose values and dose reductions with SW-IMRT differed per patient and per SWOAR and depended on N stage and tumour location. The mean reduction in predicted physician-rated Radiation Therapy Oncology Group (RTOG) grade 2-4 swallowing dysfunction was 9% (range, 3-20%). Mean reductions of the probability of patient-rated moderate to severe complaints with regard to the swallowing of solid food, soft food, liquid food and choking when swallowing were 8%, 2%, 1% and 1%, respectively. New predictive models for swallowing dysfunction were applied to show potential reductions in physician and patient-rated swallowing dysfunction with IMRT that was specifically optimised to spare SWOARs.

van der Laan HP ，Christianen ME ，Bijl HP ，Schilstra C ，Langendijk JA ... -  《-》

Swallowing sparing intensity modulated radiotherapy versus standard parotid sparing intensity-modulated radiotherapy for treatment of head and neck cancer: a randomized clinical trial.

Ashour MG ，Shouman TH ，Hassouna AH ，Mokhtar MH ，Emad El Din R ，Youssef AA ，Gomaa MM ，Abdelgeleel S ... -  《-》

Swallowing sparing intensity modulated radiotherapy (SW-IMRT) in head and neck cancer: Clinical validation according to the model-based approach.

The aim of this study was to clinically validate a multivariable normal tissue complication probability (NTCP) model for grade 2-4 swallowing dysfunction at 6months after radiotherapy or chemoradiation (SWALM6) in head and neck cancer patients treated with swallowing sparing intensity modulated radiotherapy (SW-IMRT) and to test if SW-IMRT resulted in a reduction of the prevalence of SWALM6. The primary endpoint was SWALM6. For all 186 patients, a standard IMRT (parotid sparing) and a SW-IMRT plan (additional constraints for swallowing organs at risk) was created. The difference in NTCP for SWALM6 (ΔNTCPSWALM6=NTCPstandard-NTCPSW-IMRT) was calculated. Patients were treated with SW-IMRT. The external validation of the NTCP model was analyzed by comparing performance measures. The mean ΔNTCPSWALM6 was 4.9% (range 0.01-17.3%), with a significant lower mean predicted NTCPSW-IMRT of 22.6% (95% CI 20.2-24.9%), compared to NTCPstandard of 27.5% (95% CI 24.9-29.9%) (p<0.001). There was a perfect correspondence of NTCPSW-IMRT with the observed prevalence of SWALM6 (22.6%). The overall model performance, discrimination and 'goodness of fit' were good. We externally validated the multivariable NTCP model for SWALM6 in SW-IMRT treated patients, showing reduced swallowing dysfunction by reducing the dose parameters included in this NTCP model.

Christianen ME ，van der Schaaf A ，van der Laan HP ，Verdonck-de Leeuw IM ，Doornaert P ，Chouvalova O ，Steenbakkers RJ ，Leemans CR ，Oosting SF ，van der Laan BF ，Roodenburg JL ，Slotman BJ ，Bijl HP ，Langendijk JA ... -  《-》