Lumbar pain after radiotherapy for cervical cancer may be caused by edema and congestion of pelvic tissues stimulating the lumbar region after radiotherapy, or it may be caused by unsatisfactory regression of tumor with pyelonephrosis after radiotherapy, or it may be caused by lumbar vertebral disease attack induced after radiotherapy. 1. Edema and congestion of pelvic tissues: pelvic tissues will be congested and edematous to a certain degree after radiotherapy for cervical cancer, which can stimulate pain in lumbar region. 2. Hydronephrosis: cervical cancer itself can cause ureteral obstruction and hydronephrosis, after radiotherapy, the tumor may not subside satisfactorily, or the tumor may subside gradually but the obstruction can not be lifted completely, and hydronephrosis still exists, which may lead to lumbar pain. 3. Inducing lumbar spine disease: Radiotherapy for cervical cancer can lead to the decrease of body resistance, and in the process of radiotherapy, it is often necessary to take off thicker clothes, and the waist is in direct contact with the radiotherapy bed, which may be cooled, thus inducing lumbar spine disease and resulting in lumbago. There may be other reasons for lumbar pain after radiotherapy for cervical cancer, such as lifting heavy objects during the treatment period, sprains from excessive movement, etc. Patients are advised to look for relevant causes and symptomatic treatment under the guidance of doctors.