Dose-volume parameters and clinical outcome of CT-guided free-hand high-dose-rate interstitial brachytherapy for cervical cancer

Dosimetric comparison of intra-cavitary brachytherapy technique with free-hand (intra-cavitary + interstitial) technique in cervical cancer

Purpose

The aim of the study was to dosimetrically compare intra-cavitary brachytherapy technique (ICBT) with free-hand (intra-cavitary + interstitial, IC + IS) technique.

Material and methods

Twenty seven locally advanced carcinoma cervix patients were included in the study. Patients with more than medial 1/3rd parametrial residual disease without extending upto lateral pelvic wall were included, following external beam radiotherapy (EBRT), in which cobalt-60 high-dose-rate (60Co HDR) brachytherapy source was used. Dose for both plans were 6.5 Gy × 4 fractions, 2 fractions per day, 6 hours apart, over 2 days. Free-hand brachytherapy technique, consisted of placement of central tandem and 2 ovoids along with needles without using template, was applied. Two plans were generated by activating and deactivating the needles, and compared by normalizing to V100.

Results

A total of 79 needles were applied. Using paired-t test, dosimetric comparison of both the plans was done. Free-hand plan had a significant higher mean V90 (volume receiving 90% of the dose) of 94.2% compared with 87.22% in ICBT plan (p ≤ 0.0001). Free-hand and ICBT plans presented a mean V100 values of 89.06% and 81.51% (p ≤ 0.0001), respectively, favoring free-hand plan. The mean D90 (dose to 90% volume), D98, and D100 of free-hand plan were 6.28 Gray (Gy), 4.91 Gy, and 3.62 Gy, respectively, but equivalent parameters in ICBT plan were 5.26 Gy, 3.72 Gy, and 2.61 Gy, with p value ≤ 0.0001. In both the plans, D2cc of the bladder, rectum, and sigmoid were 4.59 Gy, 3.98 Gy, 2.77 Gy, and 4.46 Gy, 3.90 Gy, 2.67 Gy, respectively, with no statistical significance.

Conclusions

Free-hand brachytherapy (IC + IS) achieves a statistically significant better dose distribution to high-risk clinical target volume (HR-CTV) comparing with ICBT technique with similar dose to organs at risk.

Recommendations of the Spanish brachytherapy group of the Spanish Society of Radiation Oncology and the Spanish Society of Medical Physics for interstitial high-dose-rate brachytherapy for gynaecologic malignancies

The present document includes consensus-based recommendations from the Brachytherapy Group (GEB) of the Spanish Society of Radiation Oncology (SEOR) and the Spanish Society of Medical Physics (SEFM) for interstitial high-dose-rate (HDR) brachytherapy (BT) for gynaecologic malignancies. A nine-item survey-which included questions on experience with interstitial BT; indications and technique; applicator type; magnetic resonance imaging (MRI)-based planning; dose; fractionation schedule; and treatment planning-was sent to all radiation oncology departments (n = 174) in Spain in 2021. Responses were received from 36 centres (50% of all centres [n = 72] with a BT unit). The consensus-based recommendations presented here are based on a review of the available literature, professional experience among the group of experts, and in-person discussions held during the annual meeting of these two societies. We describe the results of the survey and the following: indications; contraindications; patient selection; description of applicators; role of imaging in planning; contouring; dose prescription; dosimetric reconstruction; optimisation; and dose indications for cancers of the cervix, vagina, and vulva. The various clinical scenarios in which interstitial BT is used in the treatment of gynaecological tumours are described in detail, including cervix intracavitary/interstitial hybrid HDR-BT; cervix perineal templates/freehand implants; primary vaginal malignancies/vaginal recurrences; and vulvar interstitial implants.

A new technique for performing interstitial implants for gynecologic malignancies using transvaginal ultrasound guidance

Objectives

This study concerns a new technique that aims to achieve precise interstitial brachytherapy of pelvic recurrent tumors under transvaginal ultrasound (US) guidance, enhance the conformity index of the brachytherapy (BT), and improve the curative effect of radiotherapy for gynecological oncology patients with pelvic relapse.

Methods

A real-time transvaginal US-guided interstitial implant device was developed to assist in implant BT. Prior to implant brachytherapy, the size and location of the tumor in the pelvis and the interrelationship with adjacent organs were first assessed with intracavitary ultrasound. The transvaginal US-guided interstitial implant device was then placed on the endoluminal ultrasound probe, the probe was oriented intravaginally to determine a safe needle path, the implant needle was placed into the needle passage of the device, and the implant needle was inserted into the tumor tissue in the direction guided by the ultrasound puncture guide line. After the implant needle was placed in place, the cover of the transvaginal US-guided interstitial implant device was opened perpendicular to the ultrasound probe, and the needle was separated from the ultrasound probe smoothly, and then the cover was re-covered for subsequent implantation.

Results

In this study, 56 patients who underwent real-time transvaginal ultrasound-guided implantation for gynecologic oncology were enrolled, and insertion of 736 implant needles was completed. Among them, 13 patients had recurrent pelvic tumors after cervical cancer surgery and 6 patients had recurrent pelvic tumors after endometrial cancer surgery. Thirty-two patients who underwent radical radiation therapy for cervical cancer did not have adequate regression of parametrial invaded tissue after completion of standard EBRT treatment; and 5 patients had recurrent tumors in the radiation field after previous standard course of pelvic radiotherapy. The accuracy of the implant therapy was improved. The radiotherapy dose for recurrent pelvic masses was successfully increased, and the cumulative dose of external irradiation combined with BT was augmented to 80–100 Gy. The use of a new device for transvaginal implant for recurrent masses located in the lateral wall of the pelvic cavity was successful.

Conclusion

This intravascular US-guided interstitial implant device can realize interstitial implant with the shortest path under transvaginal US guidance. With convenient operation, high precision, and good security, the device not only improves the accuracy of implant therapy, but it also reduces the risks of anesthesia and organ injury, so it is suitable for widespread promotion and use.

Clinical values of transrectal ultrasound in judging GTV of cervical cancer

PURPOSE

To investigate the clinical value of transrectal ultrasound in judging the Gross Target Volume (GTV) of cervical cancer (CC).

METHODS

A total of 196 CC patients admitted to the Department of Radiotherapy, China-Japan Union Hospital, Jilin University, from January 2016 to June 2019 were selected as the study subjects. The GTVs before and after applicator insertion were determined by transrectal ultrasound and compared with those judged by MRI.

RESULTS

All 196 patients were successfully undergoing applicator insertion according to the pretreatment plan. The GTV doses reached the clinical requirements during treatment. There was no significant difference between the GTVs judged by MRI and ultrasound before insertion in terms of upper/lower diameter (MRI Before 1 vs. Ultrasound Before 1) (MB1 vs. UB1), left/right diameter (MB2 vs. UB2), or ventral/dorsal diameter (MB3 vs. UB3), and the intragroup correlation coefficients (ICC) were 0.59, 0.77, and 0.66, respectively; moreover, there was no significant difference between the GTVs judged by MRI and ultrasound after insertion in terms of MRI After one vs. Ultrasound After one (MA1 vs. UA1), MA2 vs. UA2, and MA3 vs. UA3, and the ICC values were 0.62, 0.79, and 0.76, respectively.

CONCLUSIONS

Transrectal ultrasound can satisfactorily determine the GTV of CC and has certain value in brachytherapy for CC.

Three-dimensional image-guided combined intracavitary and interstitial high-dose-rate brachytherapy in cervical cancer: A systematic review

PURPOSE

To evaluate the local control and toxicities of three-dimensional image-guided combined intracavitary and interstitial (IC/IS) high-dose-rate brachytherapy (BT) in cervical cancer through a systematic review.

METHODS AND MATERIALS

A systematic review of relevant studies was performed through the PubMed, Web of Science, and Cochrane Library databases through May 10, 2020. Articles reporting on IC/IS technology, volumetric doses to high-risk clinical target volume (HR-CTV) and organs at risk (OARs), tumor control and/or treatment-related side effects were identified. The key information, including the type of applicator, implantation technology, characteristics of implantation, volumetric doses, tumor control, and/or treatment-related side effects, was extracted. A probit model analysis between HR-CTV D90 and tumor local control was performed.

RESULTS

Twelve studies encompassing 520 patients were included in the probit model between HR-CTV D90 and the local control rate. The probit model showed a significant relationship between the HR-CTV D90 value and the local control probability, p = 0.003. The prescribed dose of 85 Gy_EQD2,10 would in theory warrant an 87.4% (95% confidence interval 82.5%-90.5%) local control rate.

CONCLUSION

IC/IS BT is an appropriate method to achieve a high therapeutic ratio for tumors with large volumes or poor responses after external irradiation in cervical cancer. The probit model showed that the dose escalation of HR-CTV D90 was helpful to improve the local tumor control rate.

Long-term effectiveness and safety of image-based, transperineal combined intracavitary and interstitial brachytherapy in treatment of locally advanced cervical cancer

PURPOSE

The aim of the study was to evaluate the impact of image-based combined intracavitary-interstitial brachytherapy (IC-ISBT) using a transperineal template in locally advanced cervical cancer treatment.

METHODS AND MATERIALS

A total of 94 patients of cervical cancer stage IIB-IVA underwent image-based transperineal interstitial brachytherapy without tandem (ISBT) or with tandem (IC-ISBT) between June 2008 and June 2018 at our institution. After pelvic chemoradiation, 42 patients underwent ISBT and 52 IC-ISBT. Dosimetric data, clinical response, and toxicity records of these patients were reviewed.

RESULTS

Clinical stage distribution was as follows: IIB: 22.4% (21), IIIA: 10.6% (10), IIIB: 56.4% (53), and IVA: 10.6% (10). Mean high-risk clinical target volume was 75.72 cc, and mean cumulative equivalent of 2 Gy per fraction for high-risk clinical target volume was 81 Gy. The median followup was 35.5 months. Overall 3- and 5-year local control, disease-free survival (DFS), and overall survival (OS) were 84% and 84%, 69.1% and 62.9%, and 80.9% and 71.5%, respectively. Local control (90.4% vs. 76.2%; p = 0.048) and DFS (78.8% vs. 57.1%; p = 0.04) were significantly better in the patients of IC-ISBT arm. IC-ISBT (hazard ratio: 0.763; 95% confidence interval 0.217, 1.38; p = 0.046) and D90 dose >85 Gy (hazard ratio: 0.957; 95% confidence interval 0.927, 1.07; p = 0.037) were predictors of better DFS on univariate analysis. Overall survival was not affected significantly by any of the factors. Grade 3 and 4 late complications were recorded in 3.2% (3) of patients and were similar in both arms (p = 0.86). However, the mean rectum 2 cc dose was significantly lower in the IC-ISBT arm (p = 0.038).

CONCLUSIONS

Combined IC-ISBT is a safe and effective approach to treat ICBT unsuitable cases. It integrates the benefits of ICBT to the adaptability of ISBT around various targets and should be practiced whenever feasible to provide superior outcomes in locally advanced cervical cancer.

The Efficacy and Late Toxicities of Computed Tomography-based Brachytherapy with Intracavitary and Interstitial Technique in Advanced Cervical Cancer

Purpose: To report the efficacy and late side effects(LSEs) of CT-based image-guided brachytherapy for the treatment of cervical cancer.

Materials: Between 2008 and 2014, 100 patients with FIGO stage IIB-IVA cervical carcinoma were analyzed. The patients received pelvic irradiation (45-50 Gy in 25 fractions) with concurrent chemotherapy, whereas the mean prescribed EBRT dose, including initial and boost doses to positive lymph nodes, ranged from 54 to 64 Gy. Afterwards, intracavitary(IC) or combined intracavitary/interstitial(IC/IS) brachytherapy was performed using a CT-based procedure with prescribed doses of 6 or 8 Gy in 3-7 fractions.

Results: The median follow-up time was 46 months. The 5-year local control, distant metastasis-free survival, and overall survival rates were 88.9%, 81.8%, 77.9%, respectively. IC/IS brachytherapy improved the HR-CTV D90 compared with IC (p<0.01). Seven patients (7.0%) had grade 2 bladder LSEs and none had grade 3/4 bladder LSEs. There was no significant relationship between bladder LSEs and the dose-volume histogram (p>0.05 for all). Thirty-seven patients (37%) had grade 2 rectal LSEs, 3(3%) had grade 3 rectal LSE. The rectum D_1cc, D_2cc, and D_5cc values were significantly higher in patients with grades 2/3 rectal toxicity than in those with grades 0/1 (p<0.05 for all). There was no grade 2 and above small bowel LSEs.

Conclusions: CT-based brachytherapy planning can achieve excellent local control with acceptable morbidity. HR-CTV D90 can increase in the IC/IS group compared with the IC group. The D_1cc, D_2cc, and D_5cc all showed excellent predictive values for rectal LSEs.

Development and clinical implementation of a new template for MRI-based intracavitary/interstitial gynecologic brachytherapy for locally advanced cervical cancer: from CT-based MUPIT to the MRI compatible Template Benidorm. Ten years of experience

PURPOSE

To study outcome and toxicity in 59 patients with locally advanced cervix carcinoma treated with computed tomography (CT)-based Martinez universal perineal interstitial template (MUPIT) and the new magnetic resonance imaging (MRI)-compatible template Benidorm (TB).

MATERIAL AND METHODS

From December 2005 to October 2015, we retrospectively analyzed 34 patients treated with MUPIT and 25 treated with the TB. Six 4 Gy fractions were prescribed to the clinical target volume (CTV) combined with external beam radiotherapy (EBRT). The organs at risk (OARs) and the CTV were delineated by CT scan in the MUPIT implants and by MRI in the TB implants. Dosimetry was CT-based for MUPIT and exclusively MRI-based for TB. Dose values were biologically normalized to equivalent doses in 2 Gy fractions (EQD2).

RESULTS

Median CTV volumes were 163.5 cm3 for CT-based MUPIT (range 81.8-329.4 cm3) and 91.9 cm3 for MRI-based TB (range 26.2-161 cm3). Median D90 CTV (EBRT + BT) was 75.8 Gy for CT-based MUPIT (range 69-82 Gy) and 78.6 Gy for MRI-based TB (range 62.5-84.2 Gy). Median D2cm3 for the rectum was 75.3 Gy for CT-based MUPIT (range 69.8-132.1 Gy) and 69.9 Gy for MRI-based TB (range 58.3-83.7 Gy). Median D2cm3 for the bladder was 79.8 Gy for CT-based MUPIT (range 71.2-121.1 Gy) and 77.1 Gy for MRI-based TB (range 60.5-90.8 Gy). Local control (LC) was 88%. Overall survival (OS), disease free survival (DFS), and LC were not statistically significant in either group. Patients treated with CT-based MUPIT had a significantly higher percentage of rectal bleeding G3 (p = 0.040) than those treated with MRI-based TB, 13% vs. 2%.

CONCLUSIONS

Template Benidorm treatment using MRI-based dosimetry provides advantages of MRI volume definition, and allows definition of smaller volumes that result in statistically significant decreased rectal toxicity compared to that seen with CT-based MUPIT treatment.

Radiotherapy for gynecologic cancer in nonagenarian patients: a framework for new paradigms

No consensus exists regarding the role of radiotherapy in the management of gynecologic cancer in nonagenarian patients. We retrospectively reviewed the outcomes of 19 consecutive nonagenarian patients with gynecologic cancer (6 endometrial cancers, 6 cervical cancers, 4 vulvar cancers, and 3 vaginal cancers) who were treated with radiotherapy. Radiotherapy was performed mainly in a palliative setting (n = 12; 63.2%), with a median dose of 45 Gy (range, 6-76 Gy). Infrequent major acute or late toxicities were reported. Among 19 patients, 9 (47.4%) experienced tumor progression, 5 (26.3%) experienced complete response, 2 (10.5%) experienced stable disease and/or partial response. At last follow-up, 12 patients (63.2%) had died; most deaths (n = 9) occurred because of the cancer. These results suggest that radiotherapy is feasible in the treatment of nonagenarian patients with gynecologic cancer.

A new template for MRI-based intracavitary/interstitial gynecologic brachytherapy: design and clinical implementation

PURPOSE

To describe the potential clinical use of a new brachytherapy applicator for gynecological tumors, with special attention to locally advanced cervical carcinoma. This device allows the combination of intracavitary radiotherapy and MRI-compatible transperineal interstitial needles. The design of this template addresses the disadvantages of currently commercially available templates: the inability of the intracavitary component to reach deep into the cervix (MUPIT), and the MRI-incompatibility of these templates (MUPIT and Syed), which necessitates use of CT imaging for the dosimetry.

MATERIAL AND METHODS

The newly developed Benidorm Template applicator allows titanium needles in a template with straight and angled holes to provide different angles of divergence to be used with currently existing MRI-compatible intrauterine tubes. It can provide total coverage of the craniocaudal and lateral extension of the tumor (intrautherus, parametrial, and paravaginal). This method is mainly indicated in advanced cervical carcinoma with bulky parametrial invasion (medial or distal), with bulky primary disease that responds poorly to external beam radiotherapy extensive paravaginal involvement (tumor thickness greater than 0.5 cm) extending to the middle or lower third of the vagina, or for disease that has invaded the bladder or rectum (stage IVA).

RESULTS

Between April 2013 until December 2014, we treated 15 patients with locally advanced cervical carcinoma employing the Benidorm Template. The median dose at D90 for the CTV was 79.8 Gy (71.5-89.9 Gy), at D2cc for the bladder it was 77.6 Gy (69.8-90.8 Gy), and at D2cc for the rectum it was 71.9 Gy (58.3-83.7 Gy). Values expressed in EQD2, assuming α/β of 10 for CTV and 3 for OAR.

CONCLUSIONS

This new applicator allows the use of MRI-based dosimetry, thus providing the advantages of MRI volume definition. As such, it facilitates determination of complete intracavitary and interstitial CTV coverage and the sparing of normal tissues.

Brachytherapy in cancer cervix: Time to move ahead from point A?

Brachytherapy forms an integral part of the radiation therapy in cancer cervix. The dose prescription for intracavitary brachytherapy (ICBT) in cancer cervix is based on Tod and Meredith's point A and has been in practice since 1938. This was proposed at a time when accessibility to imaging technology and dose computation facilities was limited. The concept has been in practice worldwide for more than half a century and has been the fulcrum of all ICBT treatments, strategies and outcome measures. The method is simple and can be adapted by all centres practicing ICBT in cancer cervix. However, with the widespread availability of imaging techniques, clinical use of different dose-rates, availability of a host of applicators fabricated with image compatible materials, radiobiological implications of dose equivalence and its impact on tumour and organs at risk; more and more weight is being laid down on individualised image based brachytherapy. Thus, computed tomography, magnetic-resonance imaging and even positron emission computerized tomography along with brachytherapy treatment planning system are being increasingly adopted with promising outcomes. The present article reviews the evolution of dose prescription concepts in ICBT in cancer cervix and brings forward the need for image based brachytherapy to evaluate clinical outcomes. As is evident, a gradual transition from "point" based brachytherapy to "profile" based image guided brachytherapy is gaining widespread acceptance for dose prescription, reporting and outcome evaluation in the clinical practice of ICBT in cancer cervix.