A two-center experience: The impact of COVID-19 on two brachytherapy programs in Ontario - virtual care, service suspension and radiation therapy workflow.

INTRODUCTION: Most brachytherapy (BT) procedures require general anesthesia and are therefore considered aerosol generating medical procedures (AGMPs). The COVID-19 pandemic impacted BT as services were prioritized by balancing the harm associated with COVID-19 infection versus the effect of delay of potentially curative treatment. This article summarizes the impact of the pandemic on BT programs in two cancer centers in a Canadian province. METHODS: As part of a quality assurance project, a retrospective study was conducted for the first five months of the pandemic (March 1 to July 31, 2020). Chart review and COVID-19 related mitigation strategies were identified by BT Clinical Specialist Radiation Therapists (bCSRT) in each center using electronic medical records, departmental reports, policies and procedures. RESULTS: Impact included start of virtual care (VC), shortened fractionation, suspension of services and workflow changes.  Both centers implemented VC strategies to reduce clinic visits: "same-day size and treat" strategy for post-operative endometrial cancer patients and virtual patient education for all patients. BT services that were suspended were low-dose-rate and high-dose-rate (HDR) prostate treatments (Center 1), lung and esophagus HDR treatments (Center 2).  Workflow changes that affected staff and patients in both centers included COVID-19 screening and the use of personal protective equipment. The centers were marginally different in workflow adjustments for AGMP procedures.  Those considered high-risk AGMP and low-risk cancer were suspended temporarily with alternate treatment strategies sought for some patients. Others had temporizing treatment such as androgen deprivation therapy to facilitate oncological safe deferral of procedures. CONCLUSION: Both BT programs delivered treatment to most patients with minimal delays and cancellations, where feasible. Some of the pandemic workflow changes continued to the current state of the pandemic. Long-term follow-up is needed to assess the impact of COVID-19 and treatment interruptions on oncologic outcomes.

Comparing dosimetry of locally advanced cervical cancer patients treated with 3 versus 4 fractions of MRI-guided brachytherapy.

PURPOSE: To demonstrate the feasibility of treating cervical cancer patients with MRI-guided brachytherapy (MRgBT) using 24 Gy in 3 fractions (F) versus a standard, more resource-intensive regimen of 28 Gy in 4F, and its ability to meet EMBRACE II planning aims. METHODS AND MATERIALS: A retrospective review of 224 patients with FIGO Stage IB-IVA cervical cancer treated with 28 Gy/4F (n = 91) and 24 Gy/3F (n = 133) MRgBT between 2016-2021 was conducted. Multivariable linear regression models were fitted to compare dosimetric parameters between the two groups, adjusting for CTVHR and T stage. RESULTS: Most patients had squamous cell carcinoma, T2b disease, and were treated with intracavitary applicator plus interstitial needles (96%). The 28 Gy/4F group had higher CTVHR (median 28 vs. 26 cm3, p = 0.04), CTVIR D98% (mean 65.5 vs. 64.5 Gy, p = 0.03), rectum D2cm3 (mean 61.7 vs. 59.2 Gy, p = 0.04) and bladder D2cm3 (81.3 vs. 77.9 Gy, p = 0.03). There were no significant differences in the proportion of patients meeting the EMBRACE II OAR dose constraints and planning aims, except fewer patients treated with 28 Gy/4F met rectum D2cm3 < 65 Gy (73 vs. 85%, p = 0.027) and ICRU rectovaginal point < 65 Gy (65 vs. 84%, p = 0.005). CONCLUSIONS: Cervical cancer patients treated with 24 Gy/3F MRgBT had comparable target doses and lower OAR doses compared to those treated with 28 Gy/4F. A less-resource intense fractionation schedule of 24 Gy/3F is an alternative to 28 Gy/4F in cervix MRgBT.

A Phase II Randomized Trial of Chemoradiation with or without Metformin in Locally Advanced Cervical Cancer.

PURPOSE: Tumor hypoxia is associated with poor response to radiation (RT). We previously discovered a novel mechanism of metformin: enhancing tumor RT response by decreasing tumor hypoxia. We hypothesized that metformin would decrease tumor hypoxia and improve cervical cancer response to RT. EXPERIMENTAL DESIGN: A window-of-opportunity, phase II randomized trial was performed in stage IB-IVA cervical cancer. Patients underwent screening positron emission tomography (PET) imaging with hypoxia tracer fluoroazomycin arabinoside (FAZA). Only patients with FAZA uptake (hypoxic tumor) were included and randomized 2:1 to receive metformin in combination with chemoRT or chemoRT alone. A second FAZA-PET/CT scan was performed after 1 week of metformin or no intervention (control). The primary endpoint was change in fractional hypoxic volume (FHV) between FAZA-PET scans, compared using the Wilcoxon signed-rank test. The study was closed early due to FAZA availability and the COVID-19 pandemic. RESULTS: Of the 20 consented patients, 6 were excluded due to no FAZA uptake and 1 withdrew. FHV of 10 patients in the metformin arm decreased by an average of 10.2% (44.4% to 34.2%) ± SD 16.9% after 1 week of metformin, compared to an average increase of 4.7% (29.1% to 33.8%) ±11.5% for the 3 controls (p = 0.027). Those with FHV reduction after metformin had significantly lower MATE2 expression. With a median follow-up of 2.8 years, the 2-year disease-free survival (DFS) was 67% for the metformin arm vs 33% for controls (p=0.09). CONCLUSIONS: Metformin decreased cervical tumor hypoxia in this trial that selected for patients with hypoxic tumor.