Tehran University of Medical Sciences Basic & Clinical Cancer Research 2228-6527 13 2 2022 03 14 127 132 Reza Ghaletaki Radiation Oncology Research Center (RORC), Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran Ali Kazemian Radiation Oncology Research Center (RORC), Cancer Institute, Tehran University of Medical Sciences, Iran Saeed Rezaei Department of Radiation Oncology, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran Fatemeh Soleimanian Radiation Oncology Research Center (RORC), Cancer Institute, Tehran University of Medical Sciences, Iran Negin Mohammadi Radiation Oncology Research Center (RORC), Cancer Institute, Tehran University of Medical Sciences, Iran Mahdi Aghili Radiation Oncology Research Center (RORC), Cancer Institute, Tehran University of Medical Sciences, Iran Nima Mousavi Darzikolaee Radiation Oncology Research Center (RORC), Cancer Institute, Tehran University of Medical Sciences, Iran Ebrahim Esmati Department of Radiation Oncology, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran 2021 12 26 2022 02 01 Background and Objective: During the COVID-19 epidemic, concerns about cancer patients undergoing radiotherapy have increased because of the numerous hospital visits which potentially may increase the risk of contracting COVID-19. We aimed to investigate the incidence of COVID-19 among patients visiting our radiation oncology department during the first and second peaks of the epidemic. Methods: In this cross-sectional study, we included all patients who underwent radiotherapy from November 2019 to September 2020. We made a telephone call to the patients and asked if they had COVID-19 during this time, and if so, how they were diagnosed? Both clinical signs or a positive PCR test were acceptable as COVID-19 diagnostic criteria. We also gathered the data regarding cancer and treatment status out of the patients’ records in the ward medical library. This study was approved by the institutional review board and ethics committee (code: IR.TUMS.VCR.REC.1399.104).  Results During the study period, 687 patients were admitted to our radiation oncology ward. The median age was 55 (IQR: 44-65) and 424 (61.7%) were female. Twenty-three (3.3%) patients developed COVID-19, 15 (65.2%) of whom were diagnosed with clinical symptoms and 8 (34.8%) with PCR. Twelve and 11 patients contracted COVID-19 in the first and second peaks of the epidemic, respectively. Even though no patients with skin cancer or sarcomas of the bone or soft tissue contracted COVID-19, the highest frequency for COVID-19 was seen among patients with intrathoracic or lung cancer with 38 times the odds of patients with head and neck cancer to catch COVID-19. The following highly susceptible patients were those with hematologic and upper GI and gynecologic cancers, respectively. We found a significant association between intrathoracic (mainly lung) cancers and being infected with COVID-19 (P-Value = 0.02). Conclusion Patients undergoing intrathoracic cancer radiotherapy are at higher risk to contract COVID-19. We believe these patients should be prioritized in any screening or case-finding program in cancer patients and also in vaccination programs. https://bccr.tums.ac.ir/index.php/bccrj/article/view/408