Small intestine tumors are rarely diagnosed as they constitute only 0.6% of all malignant tumors, including about 1-3% of malignant neoplasms of the gastrointestinal tract. They also advocate for 0.2% of deaths caused by malignant tumors. Factors that increase the risk of disease include Crohn's disease, familial adenomatous polyposis (FAP), Lynch syndrome (HNPCC - hereditary non-polyposis colorectal cancer), Peuz-Jeghers syndrome, celiac disease and acquired immunodeficiency syndrome (AIDS). Diagnosis of small intestinal tumors is difficult because the symptoms reported by patients are not characteristic. In advanced disease, the symptoms of the digestive system dominate in the form of free, bloody stools, as well as jaundice and general weakness resulting from the deepening anemia. Often, the first symptom is gastrointestinal obstruction. In the diagnosis of small intestinal tumors, modern diagnostic techniques are used, starting from imaging (computed tomography, magnetic resonance) through endoscopic examination (gastroscopy, endoscopic capsule, bi-balloon enteroscopy). Due to the rarity of small intestine and duodenum cancer, standards for dealing with patients with these tumors have not been established. In stages I to III according to AJCC, surgical treatment is used. There are no specific standards for adjuvant or palliative chemotherapy.