Researchers found the neurons in the brain that used to represent sensation in the lost limb were still functional but now driven by the stimulation of other body parts, usually the part of the body closest to the amputated limb. No standard therapy has been established for combating phantom pain although it's generally accepted that starting regional anesthesia early is important in avoiding the onset of phantom pain. At times the actual treatment for the cancer can result in pain. For example, pain from surgery may result from a surgical incision . Chronic pain can result if there has been nerve damage or other changes in the body due to the surgery.
Chemotherapy can cause pain in several ways.
Some chemotherapy drugs, referred to as vesicants , can harm tissues if they leak out of the vein. Radiation treatment can also cause pain because it can affect normal cells that surround the cancerous tumor being treated. This can sometimes cause discomfort, dry skin, difficulty swallowing or skin sores. They sense pain and then send pain messages along nerve pathways to higher centers in the brain. In the 1960s, a pair of Canadian and English researchers speculated that in addition to such pain pathways, there were also what they termed pain-suppressing gateways.