Effective treatment of pain is very important part of the management of cancer patients. From the point of view of pathophysiology, pain may induce several disturbances in the function of the respiratory, circulatory, and nervous systems. Pain limits patients' activities, with a negative effect on physical and psychological functioning. The fact that pain continuously reminds patients about the disease may lead to the development of depression and profound hopelessness. It should be kept in mind that unrelieved pain induces the suffering not only of patients but of families and careers as well. The paper will present three cases of chronic cancer pain treatment. The first is the case of a 62-year-old female with metastatic colon cancer, in which an example of proper rotation of opioid analgesics will be presented, knowing that more than 20% of patients discontinue traditional therapy due to side effects (nausea, vomiting and constipation). The second case presents a 54-year-old patient with locoregionally advanced lung cancer, treated in the wrong way regarding planning, titration, and conversion of the pain therapy; we will also show how to overcome these mistakes. The third case, the case of a patient with prostate cancer and bone metastases, illustrates the correct therapy for neuropathic cancer pain originating from bone metastases. Chronic cancer pain remains prevalent and severe for many oncology patients, especially those with advanced disease. The goal of pain management is to relieve pain to a level that provides an acceptable quality of life.