The prognostic impact of body mass index on patients with gastric adenocarcinoma and mucinous adenocarcinoma: a retrospective cohort study.

[BACKGROUND] Body mass index (BMI) is considered a negative prognostic factor in gastric cancer (GC), but its impact on different types of pathology remains controversial. The purpose of this study was to investigate the relationship between BMI and clinicopathology and its impact on the prognosis of GC, particularly between adenocarcinoma and mucinous adenocarcinoma subtypes.

[METHODS] This study analyzed 3,081 GC patients who received extensive GC surgery at Zhejiang Cancer Hospital between April 2008 and December 2019. Demographic characteristics, tumor characteristics, and survival data were reviewed from the medical records of all patients. Multivariate Cox regression analysis detected independent risk factors affecting prognosis in GC patients. Furthermore, the correlation between BMI and clinicopathological factors was analyzed using Chi-squared assays. Effects of BMI on overall survival in patients with different pathologic types of GC were determined using the Kaplan-Meier curves.

[RESULTS] Multivariate Cox regression analysis identified age (P<0.001), BMI (P<0.001), surgery (P<0.001), differentiation (P=0.03), pathological type (P<0.001), nerve invasion (P=0.01), maximum tumor diameter (P=0.05), pathologic tumor (pT) stage (P<0.001), pathologic node (pN) stage (P<0.001), carcinoembryonic antigen (CEA) (P<0.001), and cancer antigen 125 (CA125) (P<0.001) were prognostic factors for GC. Patients were divided into three groups based on BMI (kg/m): low body weight (<18.5), medium (≥18.5, <24), and high (≥24). According to the grouping criteria of BMI, 276 were determined to be in BMI low, 1,956 in BMI medium, and 849 in BMI high. The correlation between BMI and clinicopathological characteristics was confirmed by the Chi-squared test. Specifically, pathologic tumor-node-metastasis (pTNM) stage (P<0.001), nerve invasion (P<0.001), and maximum diameter (P<0.01) were correlated with the BMI. Additionally, serum levels of CEA (P=0.01) and alpha-fetoprotein (AFP) (P<0.001) were also found to be negatively correlated with BMI. Furthermore, in gastric adenocarcinoma, the higher the BMI, the better the prognosis. In mucinous adenocarcinoma, BMI had no significant impact on patient prognosis.

[CONCLUSIONS] BMI has a reference value for the prognosis of GC. Patients with a higher BMI had a significantly better prognosis in gastric adenocarcinoma. In mucinous adenocarcinoma, the prognosis of patients in the three BMI groups did not differ significantly.