Long-term clinical outcome and dosimetric comparison of tandem and ring versus tandem and ovoids intracavitary application in cervical cancer.

Purpose: The two most common applicators used in the treatment of high dose rate (HDR) intracavitary brachytherapy (ICBT) are tandem and ovoid (TO) and tandem and ring (TR). We aimed to evaluate the relationship between these treatment plans with short and long-term clinical outcomes.

Methods: This retrospective study included 50 patients who received a partial or complete response to external beam radiotherapy treatment (EBRT) and who were diagnosed with cervical cancer in our clinic between November 2015 and October 2019, including 25 TO patients and 25 TR patients. Left and right point A, high-risk clinical target volume (HR-CTV) EQD2, D0.1cc, 1cc, 2cc for the bladder, rectum, sigmoid, upper, middle, and lower vagina doses were recorded and compared according to the applicator type using the dose-volume histogram (DVH) parameter calculated from 200 computed tomography (CT) databases.

Results: Right point A dose EQD2, HR-CTVD90,95,98, D2cc rectum EQD2, upper vagina V7Gy, 10Gy, middle and lower vagina 0,1, 1, 2cc, upper vagina 5-mm lateral point dose and upper, middle, lower vagina average doses were all found to be significantly lower for TR than for TO (p<0.005).

Conclusions: Although right point A dose EQD2, HR-CTVD90,95,98 values were higher in TO than in TR, the rectum and vaginal doses also seemed more advantageous in TR. GUS and GIS toxicities, local control, distant metastasis, treatment responses and survival rates were similar in both the applicators, although vaginal toxicity was observed more in TO. Studies with a higher number of patients are warranted in the future.