Is D2 Lymphadenectomy Essential for Cytology-positive Gastric Cancer? A Retrospective Analysis

Abstract

Background: The appropriate extent of lymphadenectomy on gastric cancer patients with positive peritoneal cytology (CY1) is uncertain. This study retrospectively compared overall survival (OS) after standard and limited lymphadenectomy. Patients and Methods: The medical records from four institutions from 2004 to 2018 were reviewed and data for 91 patients with CY1, but no other distant metastases, who underwent gastrectomy were analyzed. D2 or greater lymphadenectomy and less than D2 lymphadenectomy were performed in 51 and 40 patients, respectively. Results: Full cohort analyses showed that patients who underwent D2 or greater lymphadenectomy had better prognostic nutritional indices and more such patients received postoperative chemotherapy. The OS in the group treated with D2 or greater lymphadenectomy was also significantly better (p=0.045). Twenty-seven pairs of patients were generated via propensity score matching, and analysis of their OS showed no significant difference between the groups according to lymphadenectomy (p=0.61). Conclusion: The extent of lymphadenectomy may not affect the prognoses for patients with CY1 gastric cancer.Gastric cancer was estimated to be the fourth most common cause of cancer death worldwide, behind lung, liver, and colorectal cancer, in 2016 (1). Although early gastric cancer can be cured by endoscopic resection or surgery, the prognosis of advanced gastric cancer with distant metastases is still poor. The presence of free cancer cells in the abdominal cavity, which can be determined by peritoneal lavage cytology from the pouch of Douglas during surgery, is classified as CY1 in the Japanese classification of gastric carcinoma (2), is included in distant metastasis, and is categorized as stage IV in both the Japanese classification and the International Union Against Cancer TNM classification (3). In the Japanese gastric cancer registry in 2010 (4), the 5-year overall survival (OS) rates for patients with CY0 and CY1 gastric cancer were 66.2% and 13.1%, respectively.The CCOG0301 study, a phase II study of radical surgery followed by postoperative chemotherapy with S-1 for CY1 gastric cancer, showed excellent outcomes with a median survival time (MST) of 23.1 months and a 5-year survival rate of 26% (5). In that study, gastrectomy was performed with D2 lymphadenectomy. Since that study, radical gastrectomy with D2 lymphadenectomy has been recognized as a standard therapy for CY1 gastric cancer without other distant metastases. However, in clinical practice, limited lymphadenectomy of D1+, D1, or D0 has often been performed for CY1 gastric cancer (6, 7). Because recurrences after radical gastrectomy in patients with CY1 disease were most frequently found in the peritoneum (8), radical lymphadenectomy did not seem to be associated with survival benefit. D1+ or lesser lymphadenectomy may be appropriate for CY1 gastric cancer (6). However, the optimal lymphadenectomy for CY1 gastric cancer has not yet been clarified.In this study, we hypothesized that limited lymphadenectomy was ...

Is it Necessary to Confirm Negative Margins in Gastrectomy for Peritoneal Lavage Cytology-positive Gastric Cancer?

“…When an ASD is less than 0.1, it is judged to be well balanced. In our study, ASDs after IPTW exceeded 0.1 for age, sex, and extent of gastrectomy; however, these are not significant prognostic factors according to our previous univariate analyses (7,8).…”

“…IPTW analysis using propensity scores was conducted to adjust for significant differences in patients' characteristics between the positiveand negative-margin groups. The patients' propensity scores were estimated by a logistic regression model using the following eight variables, which are based on previous univariate analyses to identify prognostic factors for OS (7,8): age, sex, PS score, extent of lymphadenectomy (standard/limited), macroscopic tumor type {type 4 (diffuse infiltrative)/other}, histological classification (differentiated/ undifferentiated), pN, and postoperative adjuvant chemotherapy (presence/absence). IPTW analysis was performed using average treatment effect on the treated: patients with negative margins were weighted by propensity score /(1−propensity score), whereas patients with positive margins were weighted by 1.…”

“…We therefore opted for IPTW analysis rather than propensity score matching. The patients' propensity scores were estimated on the basis of previous univariate analyses, which showed that PS (1-3 vs. 0), pN (3 vs. 0-2), extent of lymphadenectomy (<D2 vs. ≥D2), histological classification (undifferentiated vs. differentiated), and absence of postoperative adjuvant chemotherapy were significantly correlated with worse OS in patients with CY1 disease (8). To confirm the balance of the distribution of each covariate, we evaluated the ASD.…”