Variations and effects of bladder and rectal volume following uniform preparation procedure in cervical cancer: Five fractions of 6 Gy.

PURPOSE: To analyze the effects of different bladder and rectal volumes on the dose of organ at risks (OARs) and primary tumors following uniform preparation procedure.

MATERIAL AND

METHODS

In this retrospective study, a total of 60 patients with cervical cancer treated with external beam radiation therapy (EBRT) combined with chemotherapy and brachytherapy (BT) during 2019-2022 were included (300 insertions). Then, tandem-ovoid applicators were placed and computed tomography (CT) scanning was performed after each insertion. Delineation of OARs and clinical target volumes (CTVs) were done according to GEC-ESTRO group recommendations. Finally, doses of high-risk clinical target volume (HR-CTV) and OARs were obtained from dose volume histogram (DVH) automatically generated by BT treatment planning system.

RESULTS

Following a uniform preparation procedure, the median bladder volume of 68.36 cc (range, 29.9-235.68 cc) was in optimal agreement with the recommended bladder volume of ≤ 70 ml, which avoided more manipulation and possible risk of adverse events during general anesthesia. As the bladder filling volume increased, there was no corresponding increase in rectal, HR-CTV, and small bowel volumes, while the sigmoid colon volume decreased. The median rectal volume was 54.95 cc (range, 24.92-168.1 cc), and as the rectal volume increased, HR-CTV, sigmoid colon, and rectum volumes increased, and conversely, small bowel volume decreased. HR-CTV changes with volume affected the rectum, bladder, and HR-CTV, but not the sigmoid colon and small intestine.

CONCLUSIONS

Following a uniform preparation procedure, the bladder and rectum can also be controlled to an optimal volume (B ≤ 70 cc, R ≈ 40 cc), which is related to the dose of the bladder, rectum, and sigmoid colon.