A decision analysis comparing three strategies for peritoneal lavage cytology testing in staging of gastric cancer in China

A preoperative predictive tool to assess the need for staging laparoscopy in oesophagogastric cancer patients

INTRODUCTION

Staging laparoscopy (SL) has become commonplace in the preoperative staging pathway for oesophagogastric (OG) cancer. SL is often performed before curative treatment to examine for macroscopic peritoneal metastases (PM) or positive peritoneal cytology (PPC). The aim of this study was to develop an objective risk scoring system to predict both PM and PPC at SL.

METHODS

A prospectively collected and maintained database of all OG cancer patients treated between 2006 and 2020 was reviewed. Univariate and multivariate analyses were performed to identify risk factors for both PM and PPC at SL. A risk score was produced for both PM and PPC, and then validated internally.

RESULTS

Among 968 patients who underwent SL, 96 (9.9%) had PM and 81 (8.4%) had PPC at SL. Tumour site (p < 0.001), computed tomography (CT) T stage (p < 0.001) and N stage (p = 0.029) were significantly associated with PM at SL (p < 0.001). Tumour site (p < 0.001), biopsy histology (p = 0.041), CT T stage (p < 0.001) and N stage (p < 0.001) were significantly associated with PPC. The risk scoring model for PM included cancer site and CT T stage. This was successfully tested on the validation set (area under the receiver operating characteristic [AUROC] = 0.730). The risk scoring model for PPC included cancer site, CT T and N stage. This was successfully tested on the validation set (AUROC = 0.773).

CONCLUSIONS

The current risk scores are valid tools with which to predict the risk PM and PPC in patients undergoing SL for OG cancer and may help to avoid subjecting patients to unnecessary SL.

A decision analysis comparing three strategies for peritoneal lavage cytology testing in staging of gastric cancer in China

BACKGROUND

Positive peritoneal cytology (PCY) indicates metastasis (M1) in gastric cancer (GC) patients; both the American and Chinese guidelines recommend laparoscopic peritoneal lavage (LPL) for cytology. However, relatively high costs impair the widespread use of LPL in some resource-limited regions in China, and the cost-effectiveness of PCY testing remains unclear. Therefore, we performed a decision analysis to evaluate the cost-effectiveness of PCY testing by comparing the guideline-recommended intraoperative LPL, a newly proposed preoperative percutaneous peritoneal lavage (PPL), and a third strategy of exploratory laparotomy with no cytology testing (ELNC) among GC patients.

METHODS

We developed a decision-analytic Markov model of the aforementioned three strategies for a hypothetical cohort of GC patients with curative intent after initial imaging, from the perspective of Chinese society. We estimated costs, quality-adjusted life years (QALYs), and incremental cost-effectiveness ratios (ICERs) as primary outcomes; we also conducted one-way and probabilistic sensitivity analyses to investigate the model's robustness.

RESULTS

We found that ELNC was dominated (i.e., more expensive and less effective) by PPL and LPL. LPL was the most cost-effective method with an ICER of US$17,200/QALY compared to PPL, which was below the Chinese willingness-to-pay (WTP) threshold of US$29,313 per QALY gained. In sensitivity analyses, PPL was more likely to be cost-effective with a lower WTP threshold.

CONCLUSIONS

Cytology testing through either LPL or PPL was less expensive and more effective than ELNC among GC patients. Moreover, LPL was the most cost-effective modality at the current WTP threshold, while PPL could potentially be cost-effective in lower-income areas.