Does anyone know whether there is a limit to the number of sigmoidoscopies that a patient can have? For example, my physician performed a proctosigmoidoscopy & biopsy on a patient in Sept. The biopsy results came back positive for rectal cancer. The patient then came back to the office in Oct. for discussion on surgical resection. During this visit, my physician performed another proctosigmoidoscopy to "reevaluate the distal extent of the cancer". Any thoughts would be appreciated. Thanks!