Clinical presentation of COVID-19 can obviously vary a lot, from no symptoms or mild flu-like forms, to severe multiple organ dysfunction syndromes rather than respiratory failure (1), which might be related to the multiple organs distribution of angiotensin converting enzyme 2, the functional receptor for SARS-CoV-2 (2, 3). Experiences from all affected countries indicate that some groups in the population are at higher risk to become ill and to die from the disease. These groups are elderly and with pre-existing comorbidities. As of April 12, 2020, 132 patients have died from COVID-19 disease in Norway, with a reported mean age of 84 years, ranging from 51-104 (WHO, Folkehelsa.no). Calculations from health authorities in Norway have indicated that 1.6 million Norwegians are at higher risk of development serious illness due to the virus, and should take special precautions (fhi.no). These persons are either of high age (>65 years), smokers, obese, or persons suffering from diabetes, cancer, reduced immune system, chronic obstructive pulmonary disease (COPD) or cardiovascular disease (fhi.no). Patients with cancer are thought to be more susceptible to infection than individuals without cancer because of systemic immunosuppression caused by malignancy and / or anticancer treatments. A publication from China, reports on data from China as of January 31 2020 (4). Liang and coworkers collected and analysed 2007 cases from 575 hospitals in 31 administrative regions. All cases had laboratory confirmed COVID-19 acute respiratory disease and were admitted to hospital. Eighteen cases (1%) had a history of cancer, which is higher than the overall incidence of cancer in the Chinese population (0.29%). Of these 18 patients, the most frequent cancer was lung cancer (5/18). The cancer patients were older and more likely to have a history of smoking that the other COVID-19 patients. The authors reported that the cancer patients had a 39 % higher risk of developing severe events, compared to patients without cancer (4). The interpretation of preliminary results reported so far has been discussed, due to small numbers (5, 6). The infection has had limited impact on general health aspects in Norway yet, as efforts to “flatten the curve” of spread has been successful. Except age, little is known about which groups are at highest risk. However, many cancer patients are very worried due to the corona situation, and some seem to refrain from seeking the health care system in order to avoid the virus and exposition. In this study, we will investigate registry data to shed light on differences in risk among cancer patients. In Norway, 34000 are diagnosed with cancer annually and 280 000 (5.2 %) of the population are cancer survivors (Kreftregisteret.no). A first recent dataset has been prepared for linkage where we have nationwide data and defined all recent cancer patients still alive and treated the last 3 months with one of modalities: chemotherapy, tyrosine kinase inhibitors, immune therapy, or radiotherapy. In addition, also other treatments that can give pneumonitis such as radiotherapy the last 6 months towards a lung/mediastinal field. These criteria may be modified as the project proceeds. More than 15 000 cancer patients have been identified according to these criteria and will be studied together with all cancer patients irrespective of time of diagnosis. We will use data from the Norwegian System for Communicable diseases (MSIS), The Norwegian Cancer Registry, the Norwegian Patient Registry (NPR), The Norwegian Prescription Registry, the death registry, the cause of Death Registry and the Norwegian Pandemic Registry and Intensive Care Registry. We will determine which patients groups are more likely to be affected with serious COVID-19, depending on diagnosis, treatment, age and comorbidities. The results will be published in international fora, and the public can be advised depending on our findings.