Aim: To examine the vaginal mucosal reaction in gynecological cancer patients after re-irradiation using interstitial brachytherapy (re-ISBT) compared to initial brachytherapy.
Patients and methods: A comparison was made between re-ISBT (n=14) and the initial brachytherapy group consisting of 63 cases of intracavitary brachytherapy (ICBT) and 37 of interstitial brachytherapy (ISBT). We examined the modified Dishe score at 6, 12, 18, 24, 36, and 60 months after treatment with a median follow-up time of 41 months (range: 6-144 months). Re-ISBT was performed using 42-51 Gy in 7-8 fractions in 2-5 days (twice a day) without external irradiation.
Results: For bleeding and discharge, fewer than 10% of patients exhibited grade 1 reactions and no statistically significantly differences were found between re-ISBT and initial brachytherapy. Re-ISBT increased erythema (grade 0/1/2=29%/57%/14%) compared with initial brachytherapy (grade 0/1/2=64%/31%/5%, p=0.03). Four out of 14 patients had grade 1 ulceration or higher after re-ISBT, whereas five patients experienced grade 1 ulceration after initial in brachytherapy (p=0.001). Notably, a fistula appeared in one patient in the re-ISBT group. There is no difference between re-ISBT and fresh brachytherapy with regard to telangiectasia, stenosis and pallor reactions. Increased cumulative (previous plus present treatment) equivalent dose in a 2-Gy fraction was correlated to a higher grade of erythema and ulceration.
Conclusion: Re-ISBT increased the vaginal mucosal reaction, as shown by increased erythema and ulceration, more than initial brachytherapy, with a higher cumulative radiation dose, but the reaction was mild in almost all cases.
Keywords: Brachytherapy; gynecological cancer; high dose rate; interstitial brachytherapy; late vaginal mucosal reaction; re-irradiation.