Abstract 4355: Different strategies for peritoneal lavage cytology testing in the staging of gastric cancer: A cost-effectiveness analysis

Abstract

Abstract Background & Aims: The positive peritoneal cytology (PCY) indicates metastasis disease in patients with gastric cancer (GC); thus, the cytology testing is directly related to subsequent treatments, patients' prognoses, and medical costs. However, the cost-effectiveness of PCY testing remains unclear. We aim to evaluate the cost-effectiveness of PCY testing by comparing two active testing strategies of a guideline-recommended intraoperative laparoscopic peritoneal lavage (ILPL) and a newly proposed preoperative percutaneous peritoneal lavage (PPPL), and a third strategy of exploratory laparotomy with no cytology testing (ELNC) among GC patients. Methods: We developed a decision-analytic Markov model to compare the cost-effectiveness of the above three strategies for a hypothetical cohort of GC patients with curative intent after initial imaging, from the perspective of Chinese society. Quality-adjusted life-years (QALYs), transition probabilities and costs were modeled using data mainly from published literature. We performed base case analysis and measured incremental cost-effectiveness ratios (ICERs) for various strategies, which were compared to a willingness-to-pay (WTP) threshold that was set to a three-fold of Chinese gross domestic product (GDP) per capita, $29,313/QALY gained. Furthermore, we conducted both one-way and probabilistic sensitivity analyses to investigate the model's robustness. Results: In the base case analysis, we found that ELNC was dominated (i.e., more expensive and less effective) by PPPL and ILPL. ILPL was the most cost-effective method, with an ICER of US $16,673/QALY compared to PPPL. One-way sensitivity analyses demonstrated that the exploratory laparotomy mortality following ILPL and the peritoneal cytology prevalence were the only two influential parameters within their plausible range when assessing the cost-effectiveness of PPPL and ILPL. In the probabilistic sensitivity analyses, the probability of ILPL being cost-effective was 71.3% at the WTP threshold of $29,313/QALY; however, PPPL was more likely to be cost-effective when the willing-to-pay (WTP) threshold was below $17,020/QALY gained. Conclusion: Cytology testing for GC staging through either ILPL or PPPL dominated ELNC in patients with curative intent. Moreover, ILPL was the most cost-effective modality at the current WTP threshold, while PPPL could potentially be cost-effective in lower-income areas. Citation Format: Qifei He, Jinyi Zhu, Anqiang Wang, Xia Li, Zhaode Bu, Jiafu Ji. Different strategies for peritoneal lavage cytology testing in the staging of gastric cancer: A cost-effectiveness analysis [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4355.