Clinical study on accelerated fractionated brachytherapy for locally advanced cervical cancer: a single-center retrospective study

This study aimed to evaluate the feasibility of using same treatment plan in accelerated fractionated brachytherapy for locally advanced cervical cancer. A retrospective analysis was conducted on 20 patients with locally advanced cervical cancer. All patients underwent external beam radiotherapy ± chemotherapy combined with brachytherapy. Patients received a single applicator implantation for two BT fractions, administered 16–20 h apart. This procedure was repeated for fractions 3 and 4. MRI (MR1) and CT (CT1) scans were performed before BT, followed by second CT scan (CT2) before next fractions. Target and OAR were delineated in CT1 and CT2, and the MRI-based treatment plan was imported to calculate doses. MR1 and CT2 images were fused with CT1 to calculate volume variation, representing positional changes. Changes in the volume, position and dose of target and OAR were compared. MR1–CT1 volumes comparison showed significant differences in high-risk clinical target volume (HR-CTV), with no significant differences in intermediate-risk CTV (IR-CTV) and OAR. CT1–CT2 volumes comparison showed no significant differences in target and OAR. Volume variation of MR1–CT1 and CT1–CT2 was smaller for IR-CTV than for HR-CTV. Bladder exhibited the least volume variation, followed by rectum, while sigmoid colon and small intestine showed the greatest variation. MR1–CT1 dose comparison showed no significant differences in target and OAR. CT1–CT2 comparison revealed significant differences in sigmoid colon dose, with no significant differences in target and other OAR. In cervical cancer brachytherapy, based on the dosimetric results from this small-sample, single-institution pilot study, the accelerated fractionated brachytherapy regimen using the same treatment plan for two consecutive fractions after a single applicator implantation appears to be a feasible therapeutic strategy. In clinical practice, close monitoring of sigmoid colon dose between fractions is recommended.