Increased proportion of the squamous cell carcinoma component is associated with worse survival in resected gastric adenosquamous carcinoma: A STROBE compliant cohort study

For the diagnosis of gastric adenosquamous carcinoma (ASC), discrepancies regarding a rational diagnostic proportion of the squamous cell carcinoma (SCC) component exist among different organizations. Our study aimed to evaluate the impact of the SCC component on the survival of gastric cancer patients and identify the optimal cutoff value for the SCC component necessary for diagnosing gastric ASC. Cases of gastric cancer with an SCC component were obtained from our center and from case reports and series extracted from Medline. Univariate and multivariate analyses were conducted to compare the overall survival between groups and examine the prognostic value of various clinical parameters. We identified 45 qualified cases in published literature and 13 in our center. Forty-two of them were males and 16 females (M: F = 2.6:1). Thirty of them were Asian patients and the rest were mainly from the United States and Europe. The mean age was 61.1 years (median 64 years, range 32–84 years). The average tumor size was 6.9 cm (median 6.0 cm, range 2.0–16.0 cm). The most common location of the cancer was the lower third (39.7%). Although a statistical difference was not achieved, the Kaplan–Meier curve demonstrated that as the proportion of the SCC component in the primary lesion increased, the patients’ survival risk increased (P = .489), and the presence of the SCC component in metastatic lymph nodes also increased the risk of survival (P = .259); both of these findings indicated a negative impact of the SCC component on survival. Furthermore, we identified the optimal cutoff for the SCC component as 35% (χ(2) = 6.544, P = .011), which was subsequently validated in a Cox regression model as an independent prognostic factor (P = .026). An increased proportion of the SCC component is associated with worse survival in gastric cancer patients with an SCC component. The optimal cutoff for the proportion of the SCC component necessary for the diagnosis of gastric ASC is 35%.