Biofeedback is a treatment method that uses monitoring devices and information to help people consciously control physical processes such as heart rate, blood pressure, temperature, sweating, and muscle tension that are usually controlled automatically. Biofeedback therapy for constipation focuses on training the person to relax the pelvic floor and anal sphincter. Different types of equipment can be used, such as balloons inserted into the rectum and electrical devices to determine muscle contraction. Biofeedback for constipation has not been specifically studied in patients with cancer.