Top Line: At ASTRO 2022, we heard about a phase 2 study of single-fraction SRS for malignant celiac axis pain. Here’s the full report.
The Study: Celiac pain (or retroperitoneal pain syndrome) is common and hard to manage in patients with pancreatic cancer and other GI malignancies. In this multicenter, single-arm, phase 2 trial 125 patients with a pain level of 5-10 on the brief pain inventory and tumor involvement of the celiac plexus received palliative single fraction SRS. The celiac plexus can’t really be contoured on CT, so a surrogate CTV was generated using the lateral and anterior borders of the aorta (~8:00 to 2:00) from the top of T12 to the bottom of L2. A 5mm PTV was used. The prescription dose was 25 Gy in 1 fraction, but given the proximity to bowel, tiered target volumes were used for planning. PTV within 5mm of bowel received 10 Gy, PTV 5-10mm from bowel received 15 Gy, the expanded portion of the PTV >1cm from bowel received 20 Gy, and the celiac plexus CTV >1cm from bowel received the full 25 Gy. Here’s a description of the protocol. The bowel was limited to 1cc receiving 11 Gy (ideal) but up to 5cc could receive 12-15 Gy. At 3 weeks after treatment, 53% of patients had complete or partial pain response. The average pain score was 6.0 at baseline and decreased by 2.5 points at 3 week and 3.2 points at 6 weeks. Toxicity related to treatment was low, but 7 patients had grade 3 events.
TBL: Single-fraction SRS to the celiac plexus significantly improves pain in over half of patients with malignant retroperitoneal pain syndrome. | Lawrence, Lancet Oncol 2024
The Study: Celiac pain (or retroperitoneal pain syndrome) is common and hard to manage in patients with pancreatic cancer and other GI malignancies. In this multicenter, single-arm, phase 2 trial 125 patients with a pain level of 5-10 on the brief pain inventory and tumor involvement of the celiac plexus received palliative single fraction SRS. The celiac plexus can’t really be contoured on CT, so a surrogate CTV was generated using the lateral and anterior borders of the aorta (~8:00 to 2:00) from the top of T12 to the bottom of L2. A 5mm PTV was used. The prescription dose was 25 Gy in 1 fraction, but given the proximity to bowel, tiered target volumes were used for planning. PTV within 5mm of bowel received 10 Gy, PTV 5-10mm from bowel received 15 Gy, the expanded portion of the PTV >1cm from bowel received 20 Gy, and the celiac plexus CTV >1cm from bowel received the full 25 Gy. Here’s a description of the protocol. The bowel was limited to 1cc receiving 11 Gy (ideal) but up to 5cc could receive 12-15 Gy. At 3 weeks after treatment, 53% of patients had complete or partial pain response. The average pain score was 6.0 at baseline and decreased by 2.5 points at 3 week and 3.2 points at 6 weeks. Toxicity related to treatment was low, but 7 patients had grade 3 events.
TBL: Single-fraction SRS to the celiac plexus significantly improves pain in over half of patients with malignant retroperitoneal pain syndrome. | Lawrence, Lancet Oncol 2024