Sex Differences in the Association Between Low Skeletal Muscle Mass and Overall Survival in Patients With Gastric Cancer After Gastrectomy: A Retrospective Cohort Study.

BACKGROUND

Low skeletal muscle mass is associated with poor overall survival (OS) after gastrectomy in patients with gastric cancer, but it remains unclear whether this prognostic effect differs between men and women. This study aimed to clarify sex differences in the effect of low muscle mass on OS after gastrectomy for gastric cancer.

METHODS

This retrospective study included patients who underwent radical gastrectomy for pathological stage I-III gastric cancer between 2010 and 2017. The skeletal muscle mass index (SMI) was calculated at the level of the third lumbar vertebra, and values lower than the Asian cutoff were defined as low. We compared OS as the primary outcome stratified by sex and muscle mass. Multivariate analysis was used to investigate the prognostic factors.

RESULTS

The median follow-up duration was 66 months. Of the 653 male patients, 416 (63.7%) had a high-SMI and 237 (36.3%) had a low-SMI. Of the 382 female patients, 182 (47.6%) had a high-SMI and 202 (52.4%) had a low-SMI. Compared with the high-SMI group, the low-SMI group had significantly poorer OS in men (p < 0.001), but not in women (p = 0.177). Multivariate analyses showed that low-SMI was an independent poor prognostic factor for OS in men (hazards ratio, 2.450; 95% confidence interval, 1.202-4.994; p = 0.014) but not in women (hazards ratio, 1.417; 95% confidence interval, 0.584-3.438; p = 0.441).

CONCLUSIONS

Low SMI was independently associated with worse OS after gastrectomy in patients with gastric cancer, with a significant association in men but not in women.