[Contribution and limits of intensity-modulated reirradiation of nasopharyngeal carcinomas]

Abstract

Purpose: We report in this study, the dosimetric and carcinologic results of intensity-modulated technique for the reirradiation of nasopharyngeal carcinomas.

Patients and methods: Eight patients reirradiated with intensity-modulation technique between January 2015 and December 2017 were included. We noted for each patient: the minimum, maximum and average doses, the dose received by 95% (D95%), 98% (D98%) and 2% (D2%) of the volume to be irradiated, the homogeneity and conformity indices and doses to the organs at risk.

Results: Target volume coverage was satisfactory with a median of D95% greater than 57Gy (95% of the prescribed dose). The median maximum dose received by the spinal cord and brainstem were 8.2Gy and 18.25Gy, respectively. After a median follow-up of 14.5 months [1-29 months], five patients were in complete remission of their disease. Overall survival at 2 years was 66.7%. An increase in preexisting late toxicity after the first irradiation (now grade 2 or above) was found in four patients (50% of cases).

Conclusion: Intensity-modulation is an attractive technique for reirradiation of the nasopharynx. It allows a better conformity of the dose to the target and a reduction of the doses on the already irradiated critical organs. This offers good control of the disease with fewer severe late toxicities.

Keywords: IMRT; Nasopharyngeal carcinoma; Nasopharynx; RCMI; Reirradiation; Réirradiation.