Perioperative outcomes and long-term survival of cryosurgery on unresectable pancreatic cancer: a systematic review and meta-analysis

Background: Pancreatic cancer (PC) continues to rank as one of the deadliest forms of cancer, with the majority of patients being diagnosed with unresectable disease. The implementation of cryoablation-based comprehensive treatment is expected to lead to a reduction in tumor size and potentially achieve complete resection. However, the availability of systematic and evidence-based treatment guidelines for cryoablation in pancreatic cancer is currently limited.

Materials and methods: A computerized search was conducted in the Medline, Embase, Cochrane Library databases, and Clinicaltrials to retrieve studies published from August 1987 to June 2023. The perioperative outcomes and long-term survival of patients with locally advanced pancreatic cancer (LAPC) or metastatic pancreatic cancer (mPC) who underwent cryosurgery were systematically collected. Heterogeneity was assessed using the Cochran's Q test, and a funnel plot was implemented to evaluate publication bias. Data were pooled and analyzed using Stata 14.0 software. The Newcastle-Ottawa Quality Assessment Form tool was employed for quality evaluation.

Results: 9 studies including 368 patients were identified. The pooled overall incidence rate was 4% (95%CI: 0-14%; I²=54.06%) for acute pancreatitis, 0% (95%CI: 0-0%; I²=0.0%) for delayed gastric emptying, 0% (95%CI: 0-1%; I²=0.0%) for postoperative pancreatic fistula (POPF) or bile leakage, 2% (95%CI:0-5%; I²=0.0%) for bleeding, and 4% (95%CI: 0-12%; I²=70.46%) for fever. Our subgroup analysis revealed that the percutaneous treatment group had a lower incidence of complications compared to laparotomy, but had higher incidences of POPF, bleeding, and pancreatitis than the intraoperative group. Median overall survival (OS) varied from 5 to 16.2 months. The median survival rates at 6, 12, 24, and 36 months for patients who underwent cryosurgery were as follows: 94.9%, 64.8% (range: 4.8%-63.1%), 22.80%, and 9.5%, respectively.

Conclusion: With the advancements in cryoablation and anti-tumor therapy, cryoablation emerges as a promising treatment modality for patients with unresectable pancreatic cancer. According to existing literature, the combination of cryoablation with radioactive particle implantation or immunotherapy has demonstrated considerable efficacy and safety. However, while the majority of included data is derived from retrospective studies, it is imperative to conduct larger sample sizes or prospective trials for further validation.