Aim. To determine personalized approaches to the choice of nutritional support (NS) tactics in oncopathology, depending on the stage of carcinogenesis. Materials and methods. Nutritionists consulted 96 patients with oncopathology (colorectal cancer, pancreatic adenocarcinoma) over the period 2018-2019. The stage of carcinogenesis was determined mainly by the morphogenetic signs according to V.S. Turusov. Nutritional status was assessed according to the parameters of the known alimentation-volemic diagnosis and basic metabolic syndromes characteristics in cancer patients. The effectiveness of NS was assessed by the change in lysosomal metabolism. Statistical analysis was performed using Statistica 10 software. Results. Based on such clinical and biochemical analysis, 3 groups of patients were identified: 1) subject only to surgical treatment; 2) subject to combined treatment; 3) palliative. Corresponding to the selected groups, the concept of nutritional extinction was formulated and 3 treatment regimens were proposed, which differ in the use of additional correction of endotoxicosis, analgesic pharmaconutrients, or low-calorie diets. The effectiveness of the nutritional correction was assessed with testing lysosomal metabolism by cathepsins L using enzyme-linked immunosorbent assay. It has been shown that cathepsin L can serve as an early marker of nutritional dysfunction and nutritional prognosis. Conclusion. When determining nutritional treatment tactics in cancer patients, it is advisable to distinguish the stages of nutritional extinction. It is advisable to carry out the assessment of NS effectiveness and nutritional prognosis according to cathepsin L levels. Nutritional counseling allows to determine the tactics of neoadjuvant NS, and in some cases to make adjustments in the choice of surgical aid.