Dose to pelvic lymph nodes during brachytherapy of locally advanced cervical cancer with 60Co HDR source

This study investigated the correlation between the prescription dose and dose to the Manchester and International Commission on Radiation Units and Measurements-report 38 (ICRU-38) lymphatic trapezoid points during high-dose-rate (HDR) brachytherapy of locally advanced cervical cancer with (Cobalt-60) 60Co .

A retrospective study was designed for; patients with locally advanced cervical cancer, treated by external beam radiotherapy and concurrent weekly Cisplatin-based chemotherapy, had no extended parametrial invasion and was treated by tandem-ovoid set, from 2017 to 2020. Groupe Européen de Curiethérapie-European Society for Radiotherapy and Oncology (GEC-ESTRO) based target's volume, ICRU-89 revised version of Manchester points A and B, and ICRU-38 lymph node surrogate points were determined, and their dose was recorded. Paired sample t-test, linear regression analysis, and Pearson correlation analyses were done considering a statistical significance level of 0.05 and using IBM SPSS statistics (Version 23, IBM Crop.).

Seventy-four brachytherapy cases were included. A positive and strong correlation was observed between D₉₀ of clinical target volume (CTV_HR) and points A and B dose for CTV_HR〈 15 cc and 〉 35 cc. Strong and significant (p < 0.05) correlations were achieved between pelvic wall points dose and D₉₀ and D₁₀₀ of the obturator and between D₅₀ and hot points of internal iliac lymph nodes. A strong correlation was obtained between D₅₀ and D₉₀ of external iliac lymph nodes and their ICRU points.

Strong correlations were obtained between dose to the pelvic lymphatic chains and their historical ICRU-38 surrogate points during HDR brachytherapy of locally advanced cervical cancer patients with 60Co tandem-ovoid applicator sets. The correlation strength between point A and prescription dose highly depends on the CTV_HR volume.