DID THE SARS-COV-2 PANDEMIC PROVIDE A UNIQUE OPPORTUNITY TO DETERMINE THE MAXIMUM PROPORTION OF SINGLE FRACTION RADIOTHERAPY (SFRT) DELIVERABLE AT THE POPULATION LEVEL FOR UNCOMPLICATED PAINFUL BONE METASTASES (UPBM)?

Abstract

Purpose:

SFRT is recommended over multiple fraction radiotherapy (MFRT) for the palliative management of UPBM as supported by level 1 evidence. In routine clinical practice, barriers to SFRT use arise, leading to suboptimal SFRT utilization. The maximum proportion of SFRT achievable at the population level is currently unknown. We conducted a retrospective population-based analysis of SFRT utilization of a provincial cancer program during post-lockdown 2020 and assessed factors associated with receipt of MFRT.

Materials and Methods:

The SARS-COV-2 pandemic led to critical radiation oncology (RO) resource shortages after the first pandemic lockdowns in March 2020. In response, CancerCare Manitoba, a provincial cancer program, asked all ROs to conserve limited RT resources by prioritizing SFRT for UPBM. MFRT was permitted for individual cases if the treating RO felt a given bone metastasis did not meet criteria as an UPBM. Between 20 March 2020 to 31 December 2020, all patients treated in Manitoba with palliative RT for bone metastases were identified using the ARIA electronic medical record and patient, tumour, and treatment variables were extracted. The proportions of patients treated with SFRT and MFRT were tabulated. Univariable and multivariable logistic regression assessed factors associated with receipt of MFRT.

Results:

Following the March 2020 lockdowns, 878 bone metastases received palliative RT with a mean age of 67.5 years and the most common primary sites were lung (27.6%), prostate (22.9%), and breast (15.2%). Amongst the whole cohort, Spinal cord compression was present in 9.9%, and 36.2% of bone metastases were complicated. SFRT was used in 85.7% of uncomplicated bone metastases and 81.3% of all bone metastases. On multivariable analysis, factors associated with increased odds of MFRT included spinal cord compression (OR 2.2, p=0.005), soft tissue extension (OR 2.9, p<0.000), primary tumour types including hematologic (OR 2.8, p=0.013), non-prostate GU (OR 3.3, p=0.006), and GI (OR 2.6, p=0.020).

Conclusions:

This study found that the maximum proportion of SFRT that can be utilized for the palliation of uncomplicated bony metastases at the population level is 85.7%. Knowledge translation campaigns aimed at maximizing SFRT utilization now have an upper asymptote upon which reasonable SFRT benchmark goals can be derived.