Early stage rectal cancer usually does not cause back pain, but it is possible to cause back pain when it develops into middle or late stage. When some patients have more serious rectal cancer and the cancer cells have deteriorated and metastasized during the middle and late stages, some patients may have back pain. 1. Because of the invasion of peripheral tissues and lumbar muscles may occur in the middle and late stages of rectal cancer and cause low back pain. 2. When spinal bone metastasis occurs, it may also cause low back pain. 3. As the tumor increases in size, it may stimulate or invade the retroperitoneal nerve, which in turn may lead to pain radiating to the lumbosacral region and cause low back pain. 4. When the tumor lesion metastasizes to the kidney, resulting in pressure on the kidney tissue, it can also cause low back pain. It is recommended that patients should go to regular hospitals in time when they have uncomfortable symptoms, and receive treatment under the guidance and advice of doctors.