Cancer-related pain is a very prevalent problem in all stages, with 10% of patients requiring invasive techniques for adequate pain management. Ganglion impar neurolysis has been used in the treatment of pelvic-perineal pain with efficacy and rare complications, but only a few case or series reports in cancer patients have been published. We report the case of a patient presenting with an ovarian carcinoma (FIGO stage IIIC), who had several disease relapses at the colorectal transition and need for palliative colic prosthesis. She presented later with anorectal pain associated with a rectovaginal fistula, which had an important impact on the activities of her daily life. She was submitted to two ganglion impar neurolyses, which resulted in improved pain control for a total of 5 months, an important improvement in her quality of life, and reduction of opioid consumption. The authors aim to alert to the importance of pain control and to address the fourth step of the WHO analgesic ladder as an option for cancer patients, including palliative patients.