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Introduction: Sequential boost intensity‐modulated radiotherapy (SQB‐IMRT) uses two different planning CTs (pCTs) and treatment plans. SQB‐IMRT is a form of adaptive radiotherapy that allows for responses to changes in the shape of the tumour and organs at risk (OAR). On the other hand, dose accumulation with the two plans can be difficult to evaluate. The purpose of this study was to analyse patterns of loco‐regional failure using deformable image registration (DIR) in hypopharyngeal cancer patients treated with SQB‐IMRT. Methods: Between 2013 and 2019, 102 patients with hypopharyngeal cancer were treated with definitive SQB‐IMRT at our institution. Dose accumulation with the 1st and 2nd plans was performed, and the dose to the loco‐regional recurrent tumour volume was calculated using the DIR workflow. Failure was classified as follows: (i) in‐field (≥95% of the recurrent tumour volume received 95% of the prescribed dose); (ii) marginal (20–95%); or (iii) out‐of‐field (<20%). Results: After a median follow‐up period of 25 months, loco‐regional failure occurred in 34 patients. Dose–volume histogram analysis showed that all loco‐regional failures occurred in the field within 95% of the prescribed dose, with no marginal or out‐of‐field recurrences observed. Conclusion: The dosimetric analysis using DIR showed that all loco‐regional failures were within the high‐dose region. More aggressive treatment may be required for gross tumours. [ABSTRACT FROM AUTHOR]

Background: We investigated whether prophylactic percutaneous endoscopic gastrostomy (PEG) is used effectively for patients treated with definitive concurrent chemoradiotherapy (CCRT) and the predictors of the need for PEG. Methods: 326 patients with laryngeal, oropharyngeal or hypopharyngeal cancers were retrospectively reviewed. Results: The PEG tube use group had more favorable results than the total parenteral nutrition and nasogastric tube groups in terms of rate of serum albumin loss, incidence of severe fever and aspiration pneumonia, CCRT completion rate and hospitalization period. However, it was inferior to oral intake. Analysis of the relative risk of requiring enteral or parenteral nutrition revealed that performance status (PS) 2, primary site (supraglottis, oropharynx, or hypopharynx), N3 disease, and cisplatin were predictors of the need for nutritional support. Conclusions: Prophylactic PEG is effective for patients treated with definitive CCRT and is especially required for patients with PS2 or oropharyngeal cancer. [ABSTRACT FROM AUTHOR]

• Normal tissue complication probability (NTCP) model can guide treatment selection. • NTCP for radiation-induced liver toxicity (RILT) has been developed. • RILT risk varied among different Child–Pugh and viral hepatitis infection status. • Estimated NTCP model and ΔNTCP for RILT are specific to the patient subgroups. • ΔNTCP with uncertainty in individualized subgroups is helpful to select treatment. To predict the probability of radiation-induced liver toxicity (RILT) and implement the normal tissue complication probability (NTCP) model-based approach considering confidence intervals (CIs) to select patients for new treatment techniques, such as proton beam therapy, based on a certain NTCP reduction (ΔNTCP) threshold for primary liver cancer patients. Common Toxicity Criteria for Adverse Events (CTCAE) grade ≥2 RILT was scored. The Lyman NTCP models predicting the probability of CTCAE grade ≥2 RILT as a function of the fraction-size adjusted mean liver dose (MLD), using reference fraction size = 2 Gy/fraction and α / β ratio = 2 Gy, were fitted using the maximum likelihood method. At certain combinations of MLDs, ΔNTCP with a CI was evaluated by the delta method. Of the 239 patients, the incidence of CTCAE grade ≥2 RILT was 55% (46% in the Child–Pugh (CP)-A vs. 81% in the CP-B/C, p < 0.001). Among 180 CP-A patients, 40% who had viral hepatitis infections experienced toxicity vs. 32% in the nonhepatitis subgroup. The MLD was 18 Gy in the toxicity group vs. 16.1 Gy in the nontoxicity group (p = 0.002). The estimated NTCP model parameters specific to the patient subgroups and the ΔNTCP with CI assuming a particular CP classification and viral hepatitis infection status were considerably different which possible changed treatment decision. Patients with CP-A and viral hepatitis infection or CP-B/C cirrhosis had greater susceptibility to CTCAE grade ≥2 RILT. The estimated NTCP and ΔNTCP for individual patients along with a consideration of uncertainties improve the reliability of the NTCP model-based approach. [ABSTRACT FROM AUTHOR]