The sympathetic nervous system plays a crucial role in the transmission of visceral, neuropathic, and ischemic pain. Sympathetic blocks can reduce pain not only by interrupting afferent visceral and vascular pain signals but also by decreasing vascular tone, thereby improving tissue perfusion. Additionally, they can induce a relative parasympathetic dominance in the intestinal system, enhancing peristalsis and reducing the development of constipation—a significant issue in cancer patients.

Celiac plexus block is indicated for upper abdominal pain associated with cancer. It has been shown that neurolytic celiac plexus block improves patients' quality of life and reduces opioid consumption. One of the most common applications is pain related to pancreatic cancer. Particularly in pancreatic cancer, early application of neurolytic celiac plexus block has been recommended in several reports.

Splanchnic nerve block has been demonstrated to be effective for malignant visceral pain originating from the pancreas and stomach. Its indications are similar to those of the celiac block. Strong evidence shows that neurolytic splanchnic block provides a reduction in pain intensity and opioid consumption for up to six months, along with an improvement in quality of life. In cases where the celiac ganglion is invaded by a tumor, splanchnic nerve block may provide superior analgesic effects. It may also be effective in patients who do not respond to celiac plexus block.

In pelvic cancers, pain is generally observed in approximately 50–60% of patients. Superior hypogastric plexus block is indicated for pelvic visceral pain perceived below the umbilicus. Multiple studies have demonstrated that successful superior hypogastric plexus neurolysis can reduce pain intensity by more than 50–70%.

Perineal, external genital, and coccygeal pain are the main indications for impar ganglion block. Reports suggest that impar ganglion block can be combined with superior hypogastric plexus block in the management of pelvic and perineal pain.

Interventional techniques should not be considered a last resort in cancer pain management. They may be incorporated as part of a multimodal approach in patients who do not respond to opioids or whose quality of life is adversely affected by opioid-related side effects.