More patients are now surviving cancer thanks to early diagnosis and improved treatment. Chronic pain in cancer survivors is problematic and the risk of chronic therapy with opioids includes abuse or addiction. We describe a patient with lymphoma whose behavior became aberrant while under treatment with opioid analgesics to manage anxiety after a painful tumor disappeared. Using opioid analgesics to manage emotional distress rather than pure physical pain has been defined as chemical coping, which is considered as an early stage of abuse or addiction. Knowledge of opioid analgesics and aberrant drug-related behaviors is necessary to manage chronic pain in cancer survivors.