Adenocarcinoma of the anal canal is a rare cancer. There are a few publications dedicated to this problem only, since patients with this nosological entity are combined with groups of those with lower ampullary cancer of the rectum (despite differences in the nature of these diseases). This paper describes 2 clinical cases of multistep combination treatment for locally advanced and disseminated cancer (adenocarcinoma) of the anal canal. It shows that it is appropriate to apply an aggregate approach to diagnosing this rare disease. Successful experience in treating patients with locally advanced and disseminated cancer of the anal canal is demonstrated. Nonstandard therapeutic approaches and clinical decisions are used. Magnetic resonance imaging was a key technique to diagnose local disease advance in both cases. Radiation sensitizers with different mechanisms of action were used during chemotherapy; preference was given to organ-sparing surgical treatment in the patient with metastatic cancer to maintain quality of life. The paper gives a concise literature review of current methods for the diagnosis and treatment of this disease. Despite the fact that there are no uniform standards, most authors adhere to the opinion that treatment should be started with prolonged chemoradiation therapy cycles followed by surgery. The treatment of patients with the isseminated forms of the disease is strictly individual and calls for a special approach, by taking into account of quality of life and prognosis in a patient.