Background: Cancer patients suffer from many complications caused by both the disease itself and the side effects of anticancer treatment. Many symptoms go unnoticed by doctors because of the patient's remote location, significant interruptions between face-to-face visits to the doctor and differences in the individual course of the disease.In a pandemic caused by Covid 19, cancer patients are at great risk. The practical impossibility of patient's visit to a doctor, conduct clinical trials determines the highest risk for this group of patients. Thus the relevance of remote support for these patients in isolation increases many times. Objective: The goal was to create and implement in a pilot project a digital service (ONCONET system) for remote monitoring of cancer patients outside the hospital as well as adaptation to COVID 19 pandemic. Methods: The developed platform is a cloud service hosted in a data processing center which provides healthcare organizations with a ready-made service. The system is based on specialized questionnaires developed by oncologists for remote assessment of the patient's condition. The important component of the system are content libraries for patients and doctors, information and reference materials as the collection of video-schools from leading experts of nosology, rules of life, nutrition, rehabilitation and care. Results: To evaluate the effectiveness of the ONCONET system, 2 groups of patients were formed: ONCONET group -206 patients and retrospective control group -209 patients. Statistical analysis revealed significant differences between groups as a whole, as well as between individual factors of complications. Conclusion: The study demonstrates the usefulness and high medical efficiency of the ONCONET system for remote monitoring of cancer patients, especially against the background of a pandemic and the necessary self-isolation of cancer patients.