Not everyone with cancer experiences cancer pain, but one out of three people undergoing cancer treatment does.  If you have advanced cancer, your chance of experiencing cancer pain is even higher.  Cancer pain occurs in many ways.  Your pain may be dull, aching or sharp.  It can be constant, intermittent, mild, moderate or severe.  It can result from the cancer itself or from the lesion growing into or destroying tissue near the cancer.  As a tumor grows, it may put pressure on nerves, bones or organs, causing pain.  Most acute (short-term) pain is caused by treatment or diagnostic procedures, though radiotherapy and chemotherapy may produce painful conditions that persist long after treatment has ended.  Cancer pain can diminish the quality of life by adversely affecting mood, sleep, social relations and activities of daily living.