Dosimetric analysis of intraocular hemorrhage in nonsquamous head and neck cancers treated with carbon-ion radiotherapy

Abstract

Background and purposeCarbon-ion radiotherapy is an attractive treatment option for unresectable/inoperable, nonsquamous cancers of the head and neck. Intraocular hemorrhage associated with carbon-ion radiotherapy for head and neck cancer is largely an unresearched area; hence, we investigated its incidence and predictive factors. Material and methodsWe evaluated 79 patients (i.e., 158 eyes) with nonsquamous cancers of the head and neck treated by carbon-ion radiotherapy with a follow-up period of ≥12 months. Dosimetric parameters such as Dmax, Dmean and Vd [volume irradiated with “d” Gy (RBE)] and age, gender, primary site, histology and comorbidities were analyzed as predictors of intraocular hemorrhage. ResultsSeven (8.9%) of 79 patients (158 eyes) developed intraocular hemorrhage with a median latent period of 24 months (range, 15–47 months). The 5-year cumulative incidence of intraocular hemorrhage was 6%. Dmax and V10–60 for eyeballs, retina and optic nerves were significantly higher in intraocular hemorrhage group than the rest (p <0.001 for Dmax and V10–60). On univariate analysis, V40 ≥0.83 cm3 and ≥0.66 cm3 (p = 0.001) and Dmax ≥54.75 Gy (RBE) and ≥54.58 Gy (RBE) (p = 0.002) for eyeball and retina, respectively, were predictors of intraocular hemorrhage. Additionally, maxillary primary (p = 0.025) and younger age (age <60 years, p = 0.048) were significant risk factors for intraocular hemorrhage. ConclusionsDosimetric parameters such as V40 and Dmax for the eyeball, retina and maxillary sinus primary and younger age were significant predictors of intraocular hemorrhage following carbon-ion radiotherapy.