Our primary goal will be to investigate the analgesic efficacy of ultrasound (US)-assisted caudal epidural PRF (pulsed radiofrequency)( stimulation in patients with perineal or anal pain cancer patients using (visual analog scale (VAS) scores from 0 to 10 at the baseline (pretreatment), two, four, and eight weeks; secondary outcomes will be the effects on opioid use and total opioid use in the 24 h, quality of life, patient satisfaction and opioid and intervention related side effects.

Inclusion Criteria:

• American Society of Anesthesiology physical status of I or III (ASA), of both sex
• cancer-related anal or perineal pain

Exclusion Criteria:

• coagulopathies
• allergies to the contrast dye
• patients with moderate or significant cardiac/respiratory disease or hepatic