Objective
To externally validate head and neck cancer (HNC) photon-derived normal tissue complication probability (NTCP) models in patients treated with proton beam therapy (PBT).
Methods
This prospective cohort consisted of HNC patients treated with PBT at a single institution. NTCP models were selected based on the availability of data for validation and evaluated using the leave-one-out cross-validated area under the curve (AUC) for the receiver operating characteristics curve.
Results
192 patients were included. The most prevalent tumor site was oropharynx (n=86, 45%), followed by sinonasal (n=28), nasopharyngeal (n=27) or parotid (n=27) tumors. Apart from the prediction of acute mucositis (reduction of AUC of 0.17), the models overall performed well. The validation (PBT) AUC and the published AUC were respectively 0.90 versus 0.88 for feeding tube 6 months post-PBT; 0.70 versus 0.80 for physician rated dysphagia 6 months post-PBT; 0.70 versus 0.80 for dry mouth 6 months post-PBT; and 0.73 versus 0.85 for hypothyroidism 12 months post-PBT.
Conclusion
While the drop in NTCP model performance was expected in PBT patients, the models showed robustness and remained valid. Further work is warranted, but these results support the validity of the model-based approach for treatment selection for HNC patients.
Purpose
We evaluated acute toxicity profiles and dosimetric data for children with salivary gland tumors treated with adjuvant photon/electron-based radiation therapy (X/E RT) or proton therapy (PRT).
Methods and Materials
We identified 24 patients who had received adjuvant radiotherapy for salivary gland tumors. Data was extracted from the medical records and the treatment planning systems. Toxicity was scored according to the Common Terminology Criteria for Adverse Effects 4.0.
Results
Eleven patients received X/E RT and 13 PRT, with a median prescribed dose of 60 Gy in each group. In the X/E RT group, 54% of patients developed acute grade II/III dermatitis, 27% grade II/III dysphagia, and 91% grade II/III mucositis, and the median weight loss was 5.3% with one patient requiring feeding tube placement. In the PRT group, 53% had acute grade II/III dermatitis, 0% grade II/III dysphagia, and 46% grade II/III mucositis, with a median weight gain of 1.2%. Additionally, PRT was associated with lower mean doses to several normal surrounding midline and contralateral structures.
Conclusion
In this retrospective study of pediatric salivary tumors, PRT was associated with a favorable acute toxicity and dosimetric profile. Continued follow-up is needed to identify long-term toxicity and survival data.
Purpose: The authors aimed to illustrate the potential dose differences to clinical target volumes (CTVs) and organs-at-risk (OARs) volumes after proton adaptive treatment planning was used. Patients and Methods: The records of 10 patients with oropharyngeal cancer were retrospectively reviewed. Each patient's treatment plan was generated by using the Eclipse treatment planning system. Verification computed tomography (CT) scan was performed during the fourth week of treatment. Deformable image registrations were performed between the 2 CT image sets, and the CTVs and major OARs were transferred to the verification CT images to generate the adaptive plan. We compared the accumulated doses to CTVs and OARs between the original and adaptive plans, as well as between the adaptive and verification plans to simulate doses that would have been delivered if the adaptive plans were not used. Results: Body contours were different on planning and week-4 verification CTs. Mean volumes of all CTVs were reduced by 4% to 8% (P .04), and the volumes of left and right parotid glands also decreased (by 11% to 12%, P .004). Brainstem and oral cavity volumes did not significantly differ (all P ! .14). All mean doses to the CTV were decreased for up to 7% (P .04), whereas mean doses to the right parotid and oral cavity increased from a range of 5% to 8% (P .03), respectively. Conclusion: Verification and adaptive planning should be recommended during the course of proton therapy for patients with head and neck cancer to ensure adequate dose deliveries to the planned CTVs, while safe doses to OARs can be respected.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.