Extent of prior lung irradiation and mortality in COVID-19 patients with a cancer history

Abstract Purpose There have been nearly 200,000 deaths from SARS-CoV-2 (COVID-19) worldwide so far. Cancer history appears to be a poor prognostic factor for COVID-19 patients, though the reasons for this are unclear. In this report, we assess if extent of prior lung irradiation is a risk factor for death due to COVID-19 infection. Methods Patients who tested positive for COVID-19 between March 14th and April 15th, 2020 at our institution and previously received radiotherapy for cancer in our department were included in this analysis. Patient characteristics and metrics describing the extent of lung irradiation were tabulated. Cox regression models were used to identify predictors of death following COVID-19 diagnosis. A logistic model was used to characterize the association between mean lung radiotherapy dose and 14-day mortality risk following COVID-19 diagnosis. Results 107 patients met inclusion criteria. With a median follow-up of 7 days from COVID-19 diagnosis for surviving patients, 24 deaths have been observed. The actuarial survival rate 14 days after COVID-19 testing is 66%. Increasing mean lung dose (HR per Gy = 1.1, p=0.002), lung cancer diagnosis (HR=3.0, p=0.034), and receiving radiotherapy between one month and one year before COVID-19 testing (HR = 3.4, p=0.013) were associated with increased risk of death. Our survival model demonstrates a near linear relationship between mortality risk following COVID-19 diagnosis and mean lung radiotherapy dose. Conclusions COVID-19 patients with a history of radiotherapy for cancer have a poor prognosis, and mortality risk appears to be associated with extent of lung irradiation. Validation of these findings will be critical as the COVID-19 pandemic continues.