Sex difference of mortality by age and body mass index in gastric cancer

Mortality difference by age, sex, body mass index (BMI) in gastric cancer (GC) has been controversial. We evaluated sex-specific mortality by age and BMI. A total of 5961 patients diagnosed with GC from 2005 to 2013 in a single tertiary center were included and were followed until December 2017. The plot in goodness-of-fit-test by sex was crossed, so we performed sex-specific analysis. Overall mortality was lower in women than in men (adjusted hazard ratio [aHR], 0.72). Favor outcomes in women compared to men were observed among patients older than 60 yr (aHR, 0.64; 95% CI, 0.56–0.74), a BMI less than 25 kg/m² (aHR, 0.69; 95% CI, 0.61–0.79), and stage I (aHR, 0.46; 95% CI, 0.38–0.56). In sex-specific analysis, mortality increased in age older than 60 yr in men, whereas it increased in both extreme ages (<40 yr and ≥ 70 yr) in women. Mortality by BMI was lowest at BMI of 25–29.9 kg/m² and gradually increased according to decrease of BMI in men; aHR, 1.24 (23–24.9 kg/m²), 1.44 (18.5–22.9 kg/m²), and 2.54 (BMI<18.5 kg/m²). However, mortality decreased in patients with BMI ≥ 30 kg/m² (aHR, 0.46) in women. The sex discrepancies in GC mortality by age and BMI suggest the need for sex-specific approaches to prognostic prediction.