The different survival impacts of body mass index in elderly and non-elderly patients with gastric carcinoma.

Background: The age-dependent survival impact of body mass index (BMI) remains to be fully addressed in patients with gastric carcinoma (GC). We investigated the prognostic impacts of BMI in elderly (≥70 years) and non-elderly patients undergoing surgery for GC.
Methods: In total, 1168 GC patients were retrospectively reviewed. Patients were stratified into 3 groups according to BMI; low (<20), medium (20-25) and high (>25). The effects of BMI on overall survival (OS) and cancer-specific survival (CSS) were assessed using univariate and multivariate Cox hazards models.
Results: There were 242 (20.7%), 685 (58.7%) and 241 (20.6%) patients in the low-, medium- and high-BMI groups, respectively. The number of patients with high BMI but decreased muscle mass was extremely small (n = 13, 1.1%). Patients in the low-BMI group exhibited significantly poorer OS than those in the high- and medium-BMI group (P < 0.001). Notably, BMI classification significantly demarcated OS and CSS curves (both P < 0.001) in non-elderly patients, while did not in elderly patients (OS; P = 0.07, CSS; P = 0.54). Furthermore, the survival discriminability by BMI was greater in pStage II/III disease (P = 0.006) than in pStage I disease (P = 0.047). Multivariable analysis focusing on patients with pStage II/III disease showed low BMI to be independently associated with poor OS and CSS only in the non-elderly population.
Conclusions: BMI-based evaluation was useful for predicting survival and oncological outcomes in non-elderly but not in elderly GC patients, especially in those with advanced GC.
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