This clinical trial studies how well cesium-131 low-dose rate interstitial brachytherapy works as an organ-preserving radiation technique in the treatment of patients with cervical and endometrial cancer that has come back in the vagina after a period of improvement following pelvic radiation therapy (vaginal recurrence). In cervical and endometrial cancer patients with vaginal recurrence following pelvic radiation therapy, the only curative option involves a major surgical procedure which removes all the contents of the pelvic cavity, such as the uterus, cervix, bladder, rectum, vagina, and vulva. This procedure is complex and comes with many side effects; therefore, a need remains to improve radiation treatment techniques so radiation therapy can be offered as an alternative treatment option for these patients. Cesium-131 low-dose rate interstitial brachytherapy is a form of internal radiation therapy called brachytherapy. It uses grain-of-rice-sized radioactive seeds implanted directly into or near where the tumor has returned. The implanted seeds give off radiation to kill tumor cells for only a short time after they are placed. Most of the radiation is gone within a few weeks. The seeds stay in the body permanently, but they become inactive quickly. Cesium-131 low-dose rate interstitial brachytherapy may be an effective organ-preserving radiation technique for the treatment of cervical and endometrial cancer patients with vaginal recurrence following pelvic radiation therapy