Comparison of Significant Carotid Stenosis for Nasopharyngeal Carcinoma between Intensity-Modulated Radiotherapy and Conventional Two-Dimensional Radiotherapy

Abstract

Radiotherapy (RT) serves as the most efficient treatment for nasopharyngeal carcinoma (NPC) and can cause carotid stenosis. This work compared the incidence of significant carotid stenosis between intensity-modulated radiotherapy (IMRT) and two-dimensional conventional radiotherapy (2D-RT) for NPC and explored the risk factors. We retrospectively reviewed 233 cases with NPC who underwent carotid ultrasound post IMRT or 2D-RT from 2006 to 2015. The incidence of significant stenosis after RT was 19.3%. Significant stenosis was identified in 20 (14.6%) of 137 patients treated with IMRT and 25 (26.0%) of 96 patients with 2D-RT, respectively (p = 0.035). Multivariate logistic analysis indicated age (odds ratio = 1.054, 95% CI = 1.011–1.099, p = 0.014), radiation technique (IMRT) (odds ratio = 0.471, 95%CI = 0.241–0.919, p = 0.027) and time interval (odds ratio = 1.068, 95%CI = 1.033–1.105, p = 0.001) as independent predictors for significant carotid stenosis. Our study suggests that IMRT was associated with decreased incidence of significant carotid stenosis versus 2D-RT for NPC. Prevention and carotid ultrasound should be considered for older NPC survivors with longer interval from RT, especially those treated with 2D-RT.

Loosening Neuro-Optic Structures Dosimetric Constraints Provides High 5-Year Local Recurrence-Free Survival With Acceptable Toxicity in T4 Nasopharyngeal Carcinoma Patients Treated With Intensity-Modulated Radiotherapy

“…Despite this promising possibility of exposing NOS to higher doses, maintaining the exposure of the vast majority of nerves and chiasm segments to lower doses may be safe. In this context, it is noteworthy that, unlike conventional radiotherapy, in which a high dose is delivered to NOS targets by bilateral opposed fields, IMRT can deliver a higher radiation dose to the target region while sparing the adjacent optic nerves/chiasm by using multiple fields ( 32 ). Thus, only portions of the nerves, rather than the entire nerve, were subjected to the prescription dose at the targeted nerve level.…”

Management of Radiation Induced Carotid Stenosis in Head and Neck Cancer

“…Post-irradiation changes in the vessels develop over time. There are divergent opinions regarding the length of this period [18], [22], [23], [24], [25], [26], [27]. Cheng et al demonstrated an 8.5 times greater risk of having severe carotid stenosis in patients irradiated over 5 years ago than in those with a shorter history [24].…”

Assessing the short-term effects of radiotherapy on the shear modulus of the common carotid artery as a new biomarker of radiation-induced atherosclerosis

“…But there was no dose-response curve between the carotid absorbed dose and arterial stiffness for the head and neck patients after radiotherapy for 8 years [27]. Another study showed a significant increase in carotid artery stenosis after radiotherapy, but IMRT is lower than 2D radiotherapy [28]. Previous studies were focused on the Young elastic modulus after radiotherapy, but shear elastic modulus has not been investigated in radiation-induced vessels.…”