Comparative evaluation of the doses received by the parotid glands as predictors of xerostomia be 3D-CRT, IMRT and VMAT irradiation techniques in local advanced nasopharynx cancer

Abstract

Xerostomia is commonly associated with the radio-chemotherapy treatment of the head and neck cancers. The risk increases with increasing doses received by the parotid. Severe xerostomia (defined as long-term salivary function of < 25% of baseline) may be avoided if at least one parotid gland receives less than 20 Gy. The combined treatment with cisplatin regarded as bringing a significant benefit in survival with concurrent radiotherapy is associated with increased risk of late toxicity. Intensity-modulated radiotherapy (IMRT) is considered the radio-therapeutic standard in the management of head and neck cancer. Purpose: to evaluate the possibility of modern techniques to reduce radiation doses to parotid glands compared to conventional 3D-CRT radiotherapy even if the parotid glands are not delineated as organs at risk (OAR) and dosimetric constraints are not applied. Methods: For 10 locally advanced nasopharyngeal cancer cases treated by radiotherapy with curative intent using 3D-CRT technique, alternative IMRT and VMAT plans were proposed without applying dosimetric constraints for parotid glands. Results: IMRT and VMAT techniques reduce the maximum dose (Dmax) and the mean dose (Dmean) for both parotid glands compared to the 3D-CRT technique. The treatment plans were comparatively analyzed in terms of doses received by both parotid glands. Conclusions: Modern radiotherapy techniques implementation can reduce the dose received by the parotids even in the absence of contouring them as organs at risk, reducing xerostomia and ensuring a better quality of life for the nasopharynx cancer radio-treated patients.

Dosimetric impact of weight loss and anatomical changes at organs at risk during intensity-modulated radiotherapy for head-and-neck cancer

“…As expected, organs such as the parotid gland, optic nerve, and brainstem near the PTVs were partially irradiated by the primary radiation beams and received significantly diverse doses level than the planned doses. Increasing the doses received by parotid glands over the constraint doses may lead to xerostomia; these results are consistent with previous studies (Gabryś, Buettner, Sterzing, Hauswald, & Bangert, 2017;Hawkins et al, 2018;Lou et al, 2018;Mireștean, Buzea, Butuc, Zara, & Iancu, 2017;Richards et al, 2017;Vissink et al, 2010).…”

Comparative Dosimetric Analysis of conventional 3DCRT and VMAT for Head and Neck Cancer

“…On analysis regarding OARS, there was significant lesser mean dose to parotid glands irrespective of the stage of disease in VMAT technique which aligns with finding of study conducted by Mirestean et al [9]. The dose to parotid glands were significantly low in VMAT for each PTV volume except for PTV volume 801-900 cm 3 .…”

Radiomics Breakthrough Could Spark the Head and Neck Cancer Radiotherapy Revolution

“…Although it is a multifactorial effect, the irradiation of the parotid glands, the submandibular glands, but also the minor salivary glands is involved in treatment related xerostomia. Chronic dysphagia with risk of aspiration pneumonia, trismus, mucositis, but also radio-necrosis of the temporal lobes (especially associated with radiotherapy of the skull base region) are also related with HNC treatment (20,21).…”