Celiac plexus radiosurgery for retroperitoneal pain in advanced cancer: a pre-specified secondary analysis of health-related quality of life in a phase II single-arm trial

Background: Retroperitoneal pain syndrome seen in pancreatic cancer is a major clinical challenge. Celiac plexus radiosurgery, a new palliative technique for retroperitoneal pain syndrome, decreased pain levels in a phase II study. Here Health-Related Quality of Life (HRQOL) outcomes are reported. Methods: Evaluable patients, who were enrolled between January 2018 and December 2021, in an international single-arm Phase II ethics-approved study (NCT03323489), were included. The pre-specified secondary endpoint–change in HRQOL from baseline to 3- and 6-weeks post-treatment, was measured by the Functional Assessment of Cancer Therapy – Hepatobiliary (FACT-Hep) version 4 questionnaire. Mean change was deemed clinically significant (CS) if the lower bound of the 95% confidence interval was above the predefined minimal clinically important difference (MCID) for that outcome. Findings: Of 90 evaluable patients, 51 (57%) and 44 (49%) had HRQOL FACT-Hep scores available at 3- and 6-weeks, compared to baseline. The majority of patients had pancreatic cancer (90%) and mean daily intravenous morphine equivalent consumption was 35.9 mg (SD 67.6).The mean increase of FACT-Hep total score from baseline was 9.3 points at 3-weeks (p = 0.0017) and 19.6 points at 6-weeks (p < 0.0001, 95% CI 13–26.3), representing a statistically significant (SS) 22% improvement from baseline, with CS demonstrated at 6-weeks. A sensitivity analysis, imputing no change from baseline in patients with missing data, demonstrated similar results. On multivariable analysis, lower baseline opioid use and baseline FACT-Hep scores were associated with an increased change in FACT-Hep from baseline to 3-weeks. Interpretation: Celiac plexus radiosurgery was associated with a SS improvement in HRQOL amongst patients with retroperitoneal pain at 3-weeks, and a SS and CS improvement at 6-weeks post intervention. Funding: This study received major financial support provided by Gateway for Cancer Research (G-17-100), additional support was provided from the Israel Cancer Association (20170128 and 20181272).