ESTRO 2024 - Abstract Book

S233

Brachytherapy - Gynaecology

ESTRO 2024

We reviewed a cohort of consecutive patients treated over a 5.5 year period that spanned the introduction of interstitial brachytherapy into routine clinical practice. All the patients were treated with a dose of 45Gy in 25 fractions over 5 weeks with concurrent chemotherapy and HDR brachytherapy aiming for a combined HRCTV D90 ≥85Gy, there was no optimisation done based on the RV-RP constraint. The brachytherapy planning scans were reviewed and the RV-RP dose was measured for each fraction. Vaginal toxicities (bleeding or stenosis) were obtained and scored from clinical notes. Statistical analysis was carried out using Pearson’s correlation coefficient to assess for a correlation between the RV-RP and tumour volume. T-tests were used to assess for differences in RV-RP doses between the 2 cohorts pre and post introduction of interstitial technique, with a 2-tailed significance testing p< 0.05.

Results:

A total of 126 patients were included in this study, with a median follow up of 2.6 years.

Overall (n=126)

Intracavitary only (IC )cohort

Intracavitary

+

interstitial

(ICS)

cohort (n=41)

(n=85)

Age (median in years)

48.8 24.6 57.2

48.2 23.9 60.3

51.1 24.9 51.9

Tumour volume (median in cc)

RV-RP (median in Gy, with interquartile range)

(53.6 – 62.1)

(55.1 – 64.4)

(50.5 – 55.6)

Twenty cases had an RV-RP >65Gy, these were all in the IC cohort, of these there where 4 cases >75Gy. Vaginal toxicity was recorded at any grade in 23.9% and for grade ≥2 in 7.1%.

There was no correlation between the RV-RP dose and tumour volume (Pearson’s correlation coefficient =0.21). A very significant difference was identified in the RV-RP doses between the IC and ICS cohorts (t-test p = 3.386 x10 12). There was no difference in the RV-RP doses between the group with any grade of toxicities and the group with no toxicities (t-test p=0.2862). Also, there was no difference in the RV-RP doses with any grade of toxicities and the group who had toxicity grade ≥2 (p=0.7994 respectively).