31: Single Fraction Peripheral Lung SBRT During the Global COVID-19 Pandemic at a Cancercare Manitoba: An Analysis of Technical Feasibility and Clinical Safety

CARO 2022 (pCR). Secondary outcomes included presence of any treatment response and incidence of radiation-associated toxicity.Outcomes were analysed with univariable logistic regressions and stepwise multivariable logistic regressions.Descriptive statistics were used to characterize the sample population.Results: Ninety-seven patients met inclusion criteria.The median Charlson Comorbidity Index was 5.The median clinical T-and N-stage were 3 and 1, respectively.37.5% of patients had threatened circumferential resection margins, and the median tumour distance from the anal verge was 6cm.Patients received a radiation dose of 25 Gy in five fractions.11% of patients received short-course radiation as part of total neoadjuvant therapy (TNT), and were excluded from further analysis.44% of patients were using statins during neoadjuvant therapy.9.2% of patients had pCR and 29% had no treatment response on pathology.43% of patients had radiation-associated toxicity, with 6.3% of patients having toxicity of Grade 3 or more.Statin use was not associated with increased pCR (OR 1.63, p=0.51), however it was associated with a significantly lower incidence of no pathologic response (OR 0.31, 95%CI 0.10-0.93,p=0.04).On stepwise multivariable logistic regression, statin use (OR 0.20, 95%CI 0.04-0.94,p=0.04) and male gender (OR 0.19, 95%CI 0.04-0.77,p=0.02) were associated with decreased incidence of no pathologic response.Incidence of radiation-associated toxicity was unchanged with statin use (OR 0.83, p=0.66). Conclusions:Statin use during neoadjuvant short-course radiation for rectal cancer did not increase pCR, but was associated with pathologic treatment response.Further prospective study evaluating the use of statins in conjunction with neoadjuvant short-course radiation is warranted.