Scott Glaser

How do you do it?: Gynecologic brachytherapy best practices at high volume institutions within the United States and Canada

Definitive treatment including chemoradiation and brachytherapy for patients diagnosed with locally advanced cervical cancer requires significant multidisciplinary coordination. Our goal was to assess and share gynecologic brachytherapy best practices from high volume brachytherapy centers. A survey was sent to 42 centers within the United States and Canada that perform a high volume of complex gynecologic brachytherapy. Responses were collected from 32/42 (76%) institutions. 41% of responding institutions perform > 100 complex brachytherapy procedures per year. Most departments have >1 brachytherapist and 85% of respondents complete 1-2 complex brachytherapy procedures per day. 91% of surveyed departments have support staff specifically devoted to brachytherapy. Approximately 50% of intracavitary/hybrid procedures are performed in departmental brachytherapy suites. Institutions use MRI (35%), CT (24%) or a combination (24%) for treatment planning. 88% of respondents use sedation for tandem based procedures. Respondents cite high complexity of care, insufficient reimbursement, untimely referrals, shared operative and clinical duties, expensive applicator acquisition and complex scheduling as challenging aspects of providing brachytherapy services. Conversely, respondents cite a dedicated team, departmental brachytherapy suite, well organized coordination of procedures and personnel, anesthesia support, a full range of applicators, image-based planning near the department and supportive administration as integral components in providing brachytherapy. Most surveyed institutions have >1 brachytherapist who perform 1-2 procedures per day in a dedicated brachytherapy space with a team that assists with coordination and scheduling efforts. A well supported multidisciplinary team is vital to ensure state of the art brachytherapy which is essential in curing these challenging malignancies.

Explainable artificial intelligence analysis of brachytherapy boost receipt in cervical cancer during the COVID-19 era

Brachytherapy is a critical component of the standard-of-care curative radiotherapy regimen for women with locally advanced cervical cancer (LACC). However, existing literature suggests that many patients will not receive the brachytherapy boost. We used machine learning (ML) and explainable artificial intelligence to characterize this disparity. Patients with LACC diagnosed from 2004 to 2020 who received definitive radiation were identified in the National Cancer Database. Five ML models were trained to predict if a patient received a brachytherapy boost. The best-performing model was explained using SHapley Additive exPlanation (SHAP) values. To identify trends that may be attributable to the coronavirus disease 2019 (COVID-19) pandemic, the previous analysis was repeated and limited to 2019 to 2020. A total of 37,564 patients with LACC were identified; 5799 were diagnosed from 2019 to 2020 (COVID cohort). Of these patients, 59.3% received a brachytherapy boost, with 76.4% of patients diagnosed in 2019 to 2020 receiving a boost. The random forest model achieved the best performance for both the overall and COVID cohorts. In the overall cohort, the most important predictive features were the year of diagnosis, stage, age, and insurance status. In the COVID cohort, the most important predictive features were FIGO stage, age, insurance status, and hospital type. Of the 26 patients who tested positive for COVID-19 during their course of radiotherapy, 19 (73.1%) received a brachytherapy boost. A gradual increase in brachytherapy boost utilization has been noted, which did not seem to be significantly impacted by the onset of the COVID-19 pandemic. ML could be considered to identify patient populations where brachytherapy is underutilized, which can provide actionable feedback for improving access.

A practical guide to hybrid interstitial/intracavitary brachytherapy for locally-advanced cervical cancer

In select cases of locally advanced cervical cancer, a hybrid brachytherapy (HBT) approach consisting of a combined intracavitary (IC)/insterstitial (IS) implant can yield improved target coverage and/or decreased organ at risk dose compared to IC techniques while limiting invasiveness compared to IS techniques. The technique involves placement of transvaginal and/or perineal needles in addition to the tandem and ring/ovoids using either a specialized applicator or free-hand placement. Following applicator and needle placement, brachytherapy may then be planned using principles similar to IC or IS techniques. During treatment planning, it can be helpful to obtain both MRI and CT imaging, as plastic MRI-compatible needles do not show up well on MRI. In patients where acceptable target coverage cannot be achieved using IC alone or doses to nearby OAR are too high, HBT should be evaluated. HBT can improve both dose to target and OAR while sparing patients the morbidity of perineal template-based interstitial brachytherapy. Specific scenarios where HBT may be preferred include bulky residual primary tumor especially with poor response to EBRT, extension into the lateral parametrium, vaginal extension of tumor, and an asymmetric target. Use of HBT can typically permit extension of dose coverage by an additional 1-2 cm beyond what can be achieved with an IC alone technique. HBT allows for improved therapeutic ratio by improving target volume coverage and/or lowering doses to OARs. Brachytherapists should be trained on the practical aspects of administering HBT to be able to offer a less invasive and impactful treatment option when appropriate.