Cancer is a common disease in the world wherein every year the number of patients with cancer is increasing and become one of the leading causes of death worldwide. Most of the patients with cancer experienced moderate to severe intensity pain symptoms and syndromes that acquired the name cancer pain. For many years to this day opioids as analgesic drugs are the main treatment for patients suffering from cancer pain. The use of opioids comes with a high risk of abuse, tolerance, and some side effects, for dealing with that it is important to understand the mechanism of action of opioids, the drug interactions, and toxicity. As the cancer disease progress, more and more patients get a palliative treatment. For reaching optimal medical treatment it is required to plan an individual approach that will combine all of the patient characteristics and prepare the best supporting treatment.