Outcomes from a 3-fraction high-dose-rate brachytherapy regimen for patients with cervical cancer

Clinical Outcomes of 3 Versus 4 Fractions of Magnetic Resonance Image-Guided Brachytherapy in Cervical Cancer

PURPOSE

Magnetic resonance image-guided brachytherapy is essential in the management of locally advanced cervical cancer. This study compares disease and toxicity outcomes in cervical cancer patients treated with 24 Gy/3 fractions (Fr) versus the conventional 28 Gy/4 Fr.

METHODS AND MATERIALS

This retrospective study included 241 consecutive patients with International Federation of Gynecology and Obstetrics 2018 stage IB to IVA cervical cancer treated with definitive chemoradiation between April 2014 and March 2021. Disease-free survival (DFS) was estimated using the Kaplan-Meier method and compared using the log-rank test. Cumulative incidence of local failure (LF), distant failure (DF), and G2+ gastrointestinal (GI), urinary and vaginal toxicity were estimated using the cumulative incidence function with death as a competing risk and compared using Gray's test.

RESULTS

Of the 241 patients, 42% received 24 Gy/3 Fr and 58% received 28 Gy/4 Fr. With a median follow-up of 3.2 (range, 0.2-9.2) years, there were 14 local, 41 regional nodal, and 51 distant failures in 63 (26%) patients. No significant differences were found between the 24 Gy/3 Fr and 28 Gy/4 Fr groups in 3-year DFS (77% vs 68%, P = .21), the 3-year cumulative incidence of LF (5% vs 7%, P = .57), DF (22% vs 25%, P = .86), G2+ GI toxicity (11% vs 20%, P = .13), or G2+ vaginal toxicity (14% vs 17%, P = .48), respectively. The 3-year cumulative G2+ urinary toxicity rate was lower in the 24 Gy/3 Fr group (9% vs 23%, P = .03).

CONCLUSIONS

Patients with cervical cancer treated with 24 Gy/3 Fr had similar DFS, LF, DF, GI, and vaginal toxicity rates and a trend toward a lower G2+ urinary toxicity rate compared with those treated with 28 Gy/4 Fr. A less resource-intensive brachytherapy fractionation schedule of 24 Gy/3 Fr is a safe alternative to 28 Gy/4 Fr for definitive treatment of cervical cancer.

Current Status and Future Directions of Image-Guided Adaptive Brachytherapy for Locally Advanced Cervical Cancer

PURPOSE

The standard of care for patients with locally advanced cervical cancer is definitive chemoradiation followed by a brachytherapy boost. This review describes the current status and future directions of image-guided adaptive brachytherapy for locally advanced cervical cancer.

METHODS

A systematic search of the PubMed and Clinicaltrials.gov databases was performed, focusing on studies published within the last 10 years. The search queried "cervical cancer [AND] image-guided brachytherapy [OR] magnetic resonance imaging (MRI) [OR] adaptive brachytherapy".

DISCUSSION

The retroEMBRACE and EMBRACE-I trials have established the use of MRI as the standard imaging modality for brachytherapy application and planning. Quantitative imaging and radiomics have the potential to improve outcomes, with three ongoing prospective studies examining the use of radiomics to further risk-stratify patients and personalize brachytherapy. Another active area of investigation includes utilizing the superior soft tissue contrast provided by MRI to increase the dose per fraction and decrease the number of fractions needed for brachytherapy, with several retrospective studies demonstrating the safety and feasibility of three-fraction courses. For developing countries with limited access to MRI, trans-rectal ultrasound (TRUS) appears to be an effective alternative, with several retrospective studies demonstrating improved target delineation with the use of TRUS in conjunction with CT guidance.

CONCLUSIONS

Further investigation is needed to continue improving outcomes for patients with locally advanced cervical cancer treated with image-guided brachytherapy.

Safe dose escalation and reduction of the fraction number of uterine cervical brachytherapy using a gel spacer in the rectovaginal and vesicouterine septum: A planning study

PURPOSE

To evaluate the possibility of dose escalation and reduction of fraction number in cervical brachytherapy using a gel spacer.

MATERIAL AND METHODS

Twenty patients with uterine cervical cancer treated with image-guided adaptive brachytherapy (IGABT) were selected. Hyaluronic acid gel injection (HGI) was performed in the rectovaginal and vesicouterine septum for 10 patients. The other ten patients were not with HGI. Both groups were treated with IGABT involving tandem/ovoid or cylindrical applicators along with additional interstitial needles. Dose distributions approved by radiation oncologists were retrospectively analyzed, and a dose summation of 45 Gy/25 of external beam radiation therapy and IGABT was performed. Dose constraints for D2cc of bladder, rectum, and sigmoid were 80, 70, and 70 Gy, respectively. Equivalent dose in 2-Gy fractions calculations used α/β = 10 Gy for high-risk clinical target volume (CTVHR) D90 and α/β = 3 Gy for organs at risks (OARs). As a planning study, dose distribution rescaling was conducted to deliver as much dose to CTVHR D90 as possible within the dose constraint limitation for OARs when IGABT was performed for four, three, and two fractions in both groups.

RESULTS

The median CTVHR D90 was >80 Gy in the non-HGI group and >85 Gy in the HGI group for virtual two and three fractions. Rectum D2cc was significantly lower in the HGI group for three fractions (p < 0.01).

CONCLUSIONS

In the HGI group, adequate dose delivery to CTVHR could be achieved with a reduced IGABT fraction number while meeting the dose constraints of OARs.

Hypofractionated Radiotherapy in Gynecologic Malignancies-A Peek into the Upcoming Evidence

Radiotherapy (RT) has a fundamental role in the treatment of gynecologic malignancies, including cervical and uterine cancers. Hypofractionated RT has gained popularity in many cancer sites, boosted by technological advances in treatment delivery and image verification. Hypofractionated RT uptake was intensified during the COVID-19 pandemic and has the potential to improve universal access to radiotherapy worldwide, especially in low-resource settings. This review summarizes the rationale, the current challenges and investigation efforts, together with the recent developments associated with hypofractionated RT in gynecologic malignancies. A comprehensive search was undertaken using multiple databases and ongoing trial registries. In the definitive radiotherapy setting for cervical cancers, there are several ongoing clinical trials from Canada, Mexico, Iran, the Philippines and Thailand investigating the role of a moderate hypofractionated external beam RT regimen in the low-risk locally advanced population. Likewise, there are ongoing ultra and moderate hypofractionated RT trials in the uterine cancer setting. One Canadian prospective trial of stereotactic hypofractionated adjuvant RT for uterine cancer patients suggested a good tolerance to this treatment strategy in the acute setting, with a follow-up trial currently randomizing patients between conventional fractionation and the hypofractionated dose regimen delivered in the former trial. Although not yet ready for prime-time use, hypofractionated RT could be a potential solution to several challenges that limit access to and the utilization of radiotherapy for gynecologic cancer patients worldwide.

Dose and fractionation regimen for brachytherapy boost in cervical cancer in the US

PURPOSE

Curative-intent radiotherapy for locally advanced and select early stage cervical cancer in the US includes external beam radiotherapy (EBRT) with brachytherapy. Although there are guidelines for brachytherapy dose and fractionation regimens, there are limited data on practice patterns. This study aims to evaluate the contemporary utilization of cervical cancer brachytherapy in the US and its association with patient demographics and facility characteristics.

METHODS

We retrospectively analyzed clinical covariates of cervical cancer patients diagnosed and treated in 2018-2020 with curative-intent radiotherapy from the 2020 National Cancer Database. Associations between patient and institutional factors with the number of brachytherapy fractions were identified with logistic regression. Factors with association (p < 0.10) were then included in a multivariable logistic regression model. All tests were two-sided with significance <0.05 unless specified otherwise.

RESULTS

Among the eligible 2517 patients, 97.3% received HDR or LDR and is further analyzed. More patients received HDR than LDR brachytherapy (98.9% vs 1.1%) and intracavitary than interstitial brachytherapy (86.4% vs 13.6%). The most common number of HDR fractions prescribed were 5 (51.0%), 4 (32.9%), and 3 (8.6%). After adjusting for the other variables in the model, ethnicity, private insurance status, overall insurance status, and facility type were the only factors that were significantly associated with the number of brachytherapy factions (p < 0.0001, p = 0.028, p = 0.001, and p < 0.0001, respectively, n = 2184).

CONCLUSIONS

In the US, various HDR brachytherapy regimens are utilized depending on patient and institutional factors. Future research may optimize cervical cancer brachytherapy by correlating specific dose and fractionation regimens with patient outcomes.