Cancer pain can result from the cancer itself. Cancer can cause pain by growing into or destroying tissue near the cancer. Cancer pain can come from the primary cancer itself — where the cancer started — or from other areas in the body where the cancer has spread (metastases). As a tumor grows, it may put pressure on nerves, bones or organs, causing pain. Cancer pain may not just be from the physical effect of the cancer on a region of the body, but also due to chemicals that the cancer may release in the region of the tumor. Treatment of the cancer can help the pain in these situations. Cancer treatments — such as chemotherapy, radiation and surgery — are another potential source of cancer pain. Surgery can be painful, and it may take time to recover. Radiation may leave behind a burning sensation or painful scars. And chemotherapy can cause many potentially painful side effects, including mouth sores, diarrhea and nerve damage.