Our study used a propensity score-matched analysis to reduce selection biases. This more scientific and rigorous analysis provided more reliable evidence. The results of the study demonstrated that the 3-year OS rate of patients with LSMM was 64.6%, which was significantly poorer than those with non-LSMM (77.9%) (P = 0.016) and that LSMM was an independent risk factor for overall survival in patients with GC. Furthermore, preoperative LSMM may be particularly useful in advance GC. However, the results in our study showed that LSMM is not associated with the incidence of postoperative complications.
Several clinical studies have reported that LSMM might be an unfavorable factor for the short-time outcomes and prognosis[15–18], but some existing have shown contrasting results[19–22]. Katsunobu et al.[19] have shown that there is no relationship between preoperative LSMM and postoperative complications. Kuroki, L. M. et al.[21] also indicate that LSMM has no negative impact on postoperative complications or overall survival among endometrial cancer patients. The different conclusions may be due to: 1. Different studies have different diagnostic criteria for low skeletal muscle mass; 2. Different tumor types may lead to different conclusions; 3. Different treatment methods; 4. Different races. In our hospital, laparoscopic gastrectomy accounts for more than 80% of gastric cancer operations. Therefore, we only included patients who underwent laparoscopic gastrectomy. In this study, the diagnostic criteria for LSMM came from a research based on Asian populations, which is suitable for the included population. In addition, the application of PSM analysis makes the research conclusions more reliable. Skeletal muscle mass is an excellent indicator for assessing the physical condition, and it is more objective to reflect the nutritional status of the body than Body Mass Index (BMI).
The reason why people pay attention to skeletal muscle mass is that the change of skeletal muscle mass is closely related to the postoperative outcome. For those patients with severe skeletal muscle depletion before surgery, clinicians should comprehensively evaluate and formulate more scientific treatment strategies, such as nutritional support treatment[23, 24]. Studies have shown that nutritional support program and exercise are effective way to improve postoperative outcomes in patients with GC[25].
In this study, we divided patients into early stage and advanced stage GC for analysis. The results showed that there was significant difference in 3-year OS between the LSMM group and the non-LSMM group in advanced GC (P = 0.0343), but no difference was found in early GC (3-year OS, 85.16% vs 93.55%, P = 0.2864). The initial hypothesis of the study was that the two groups can show differences in early and advanced GC. This is an interesting discovery, and no relevant research has been reported so far. We will continue to follow up these patients to further observe the impact of LSMM on the prognosis of patients with early GC.
CT is a routine examination for patients with GC before surgery, so it is feasible to use CT to assess skeletal muscle mass. It will not bring additional economic burden to patients. This study is a single-center retrospective study. The main purpose is to clarify the relationship between preoperative skeletal muscle mass and prognosis in patients with GC. CT was used to assess the preoperative skeletal muscle mass and found high-risk patients. This is of great significance to the scientific diagnosis and treatment of GC patients.
There are some potential limitations in this study. This study is a retrospective single-center study, the data integrity may be insufficient. We plan to conduct a prospective study to further explore the adverse effects of LSMM.