Clinical analysis of speculum-based vaginal packing for high-dose-rate intracavitary tandem and ovoid brachytherapy in cervical cancer

Comparison of vaginal gauze packing technique with or without balloon in high-dose-rate brachytherapy of uterine cervical cancer: A crossover randomized controlled trial

Purpose

To compare the rectal and bladder doses using two different vaginal packing techniques among uterine cervical cancer patients receiving high-dose-rate (HDR) intracavitary brachytherapy (ICBT).

Material and methods

Forty-five patients with cervical cancer were randomized to receive two sessions of ICBT using tandem and ring applicator (Varian^©), following completion of pelvic external beam radiotherapy treatment. The procedure was performed with vaginal balloon plus gauze packing or vaginal gauze packing alone, each of which was used in one of two sessions. Sequence of the type of vaginal packing was chosen with computer-generated block randomization. A HDR dose of 8.5 Gy was prescribed to point A in all patients. Volumetric dose parameters, such as D_0.1cc, D_0.5cc, D_1cc, and D_2cc of the rectum and bladder were compared between the two techniques of vaginal packing.

Results

The mean age of patients was 51 years. Majority (88%) of patients had locally advanced stages of cancer at baseline (stage IIB or more). Rectal doses were significantly less in combined packing technique (D_0.1cc: 7.52 Gy vs. 9.02 Gy, p = 0.01; D_0.5cc: 6.46 Gy vs. 7.42 Gy, p < 0.01; D_1cc: 5.91 Gy vs. 6.7 Gy, p < 0.01; D_2cc: 5.29 Gy vs. 5.97 Gy, p < 0.01). Bladder doses were higher in the combined packing technique (D_0.1cc: 11.20 Gy vs. 10.76 Gy, p = 0.18; D_0.5cc: 9.64 Gy vs. 9.32 Gy, p = 0.56; D_1cc: 8.64 Gy vs. 8.36 Gy, p = 0.55; D_2cc: 7.56 vs. 7.33 Gy, p = 0.55).

Conclusions

Combined vaginal packing resulted in statistically significant reduction in rectal radiation dose compared with standard vaginal gauze packing in high-dose-rate brachytherapy of cervix cancer using tandem and ring applicators.

Demographic and clinical factors associated with variations in opioid administration using conscious sedation during HDR brachytherapy for cervical cancer

PURPOSE/OBJECTIVES To examine patient characteristics that predispose to higher opioid administration during tandem and ovoid (T&O) high-dose rate (HDR) brachytherapy. METHODS A single-institution retrospective review was performed on patients who underwent brachytherapy for cervical cancer. Patients were included if they received at least one fraction of HDR T&O brachytherapy with analgesia administration recorded in the Medication Administration Record. Fentanyl dose was dichotomized as "low" (mean <125 μg per fraction), or "high" (mean ≥ 125 μg per fraction). Descriptive statistics and multiple logistic regression analysis were performed comparing mean opioid dose per fraction with demographic and clinical information. RESULTS From July 2014 through May 2020, 113 patients underwent 531 T&O HDR brachytherapy fractions with oral benzodiazepine and intravenous opioid fentanyl for conscious sedation. The median opioid dose per fraction was 100 μg fentanyl (range 0-250 μg). Using multiple logistic regression analysis, younger age (OR 1.071, p = 0.002) and higher BMI (OR 1.091, p = 0.019) were associated with increased opioid administration during brachytherapy. Black women received less opioid during brachytherapy when compared to White women (OR 0.296, p = 0.047). FIGO stage, ECOG score, smoking status, prior narcotic use, prior illicit drug use, parity, prior cervical procedure, Smit sleeve placement, and distance to treatment center were not associated with high opioid dose. CONCLUSION Cervical cancer patients who are younger or have higher BMI receive more narcotic analgesia during HDR brachytherapy whereas Black women received less narcotic analgesia, irrespective of age and BMI. This underscores the immediate need to address how pain is assessed and managed during brachytherapy.

Reproducibility of vaginal immobilization balloons in situ overnight for cervical cancer brachytherapy

Purpose

The use of vaginal immobilization balloons placed into the vagina for immobilization of tandem and ovoid (T+O) applicator during high-dose-rate (HDR) brachytherapy delivery has been used at our institution, and seems to have improved our patient comfort, decreased procedure time, and minimized applicator misplacement. We aimed to show that these balloons, while originally marketed for single-day use, are safe and maintain applicator positioning/dosimetry when left in situ overnight for treatment delivery on sequential days.

Material and methods

Forty-two paired computed tomography (CT) scans from thirteen patients who underwent T+O HDR treatments on sequential days with vaginal immobilization balloons in situ overnight were retrospectively compared to calculate mean change of balloon volumes and balloon/T+O distance to bony landmarks. Dosimetric planning was retroactively performed on day 2 using CT scan of each pair, and the change in estimated radiation delivery to the bladder and rectum was compared.

Results

No statistically significant overnight changes were found in balloon volumes or anterior balloon positioning. The posterior balloon shifted -0.29 ±0.46 cm (p = 0.03) to the anterior public symphysis and 0.32 ±0.50 cm (p = 0.01) to the right femoral head. The tandem shifted 0.37 ±0.39 cm (p = 0.002) to the pubic symphysis. There was no significant difference found in radiation delivered to the bladder or rectum between the paired scans.

Conclusions

This study showed minimal change in balloon volumes, balloons/T+O positioning, or in radiation dose to bladder and rectum when the applicator remained overnight. These findings support that inflatable vaginal immobilization balloons remaining in situ overnight for additional HDR T+O treatments on sequential days, is safe and provides stable dosimetry.

A comparison of tandem ring and tandem ovoid treatment as a curative brachytherapy component for cervical cancer

Purpose

The standard treatment for locally advanced stage cervical cancer is definitive radiotherapy, the quality of which affects both survival and side effects. Brachytherapy is a major component of definitive radiotherapy; it is administered using different techniques and applicators. The purpose of this study was to dosimetrically compare tandem ovoid (T-ovoid) and tandem ring (T-ring) brachytherapy treatments.

Material and methods

Both applicator sets were applied to the same 20 patients, and treatment plans were made three-dimensionally (3D), with high-risk clinical target volume (HR-CTV) and organs at risk contoured. The HR-CTV was defined according to post-external magnetic resonance results. The patients with residual tumors not exceeding one-third of the parametrium were included in this study, while patients with larger masses were excluded and received interstitial therapy. The doses were calculated for both plans. Optimization for the HR-CTV was made with the aim that the equivalent dose according to 2 Gy (EQD₂) of 90% of the HR-CTV (D₉₀) would be higher than 85 Gy, without exceeding the maximum dose for organs at risk. Then, pairwise dosimetric comparisons were performed.

Results

Plans were compared dosimetrically according to the HR-CTV, point A and B doses, and organs at risk. Although the point A and B doses were higher with T-ovoid use, the 3D HR-CTV coverage was statistically better with T-ring application (EQD₂ of HR-CTV D₉₀: 97.46 Gy for T-ring and 88.44 Gy for T-ovoid; p < 0.0001). In addition, the rectum and bladder doses were statistically lower with T-ring usage (EQD₂ of rectum, 2 cc; T-ring, 63.10 Gy; T-ovoid, 74.99 Gy; p < 0.0001; EQD₂ of bladder, 2 cc; T-ring, 85.26 Gy; T-ovoid, 89.05 Gy; p < 0.0001).

Conclusions

In our study with a limited number of samples, T-ring applicator seems to offer better 3D brachytherapy dosimetry for both HR-CTV and nearby organs at risk.

Dosimetric effects of the Smit sleeve on high-dose-rate brachytherapy tandem and ovoids plans for patients with locally advanced cervical cancer

Purpose

Smit sleeves are used to facilitate insertion of the intrauterine tandem during brachytherapy for cervical cancer. When a tandem and ovoids system is used the base of the Smit sleeve displaces the ovoids distally. The dosimetric impact of this displacement is not known. Herein we performed a dosimetric analysis to quantify this impact on the integral dose and dose delivered to the organs at risk (OARs).

Material and methods

Eleven high-dose-rate brachytherapy plans in which a Smit sleeve was used with a tandem and ovoids were reviewed. A second set of plans was generated modifying the position of the ovoids to simulate absence of the Smit sleeve. The high-risk clinical tumor volume (HR-CTV) dose coverage was maintained the same for both sets of plans by appropriately rescaling the dwell times of the simulated plan. The mean integral dose, D_2cc to the OARs (bladder, bowel, sigmoid and rectum) and the ICRU rectum point dose were compared between the original and modified plans using a paired two-sample t-test.

Results

Simulating removal of the Smit sleeve was associated with an average reduction in the mean integral dose of 6.1% (p < 0.001) and an average reduction of 10.9% (p = 0.004) to the rectal D_2cc. Doses to the remaining OARs decreased to a lesser magnitude with only that of the sigmoid being statistically significant.

Conclusions

The use of a Smit sleeve with a tandem and ovoids system could lead to the delivery of a higher mean integral dose to achieve similar HR-CTV coverage. In addition, it could increase the dose to surrounding OARs, primarily the rectum. The clinical significance of these findings is unknown, but the potential dosimetric impact of using a Smit sleeve should be taken into consideration during the planning when this device is used.