We investigated the clinical impact of sarcopenia on short-term outcomes after esophagectomy in Japanese patients with esophageal cancer. In our study, the sarcopenia group had a lower BMI and worse PS than did the non-sarcopenia group. Patients with sarcopenia also lost more blood during surgery and had shorter OS times. Furthermore, multivariate analysis identified sarcopenia as an independent indicator of worse postoperative OS in patients with ESCC.
Sarcopenia in cancer patients has received increasing attention in recent years15). Many studies have described its effects on postoperative outcomes in patients with esophageal cancer. As an example, our recent meta-analysis of 41 studies with 5965 patients revealed significant associations between sarcopenia and both OS and the postoperative complications16). However, unlike the present study, most previous studies measured skeletal muscle mass using computed tomography and diagnosed sarcopenia using the SMI only, with different cut-off values. Definitions of sarcopenia also varied widely among the previous reports, and only a few diagnosed sarcopenia before surgery based on a complete assessment of skeletal muscle mass, muscle strength, and physical performance, as was done here. Using the AWGS 2019 diagnostic criteria for sarcopenia, we found that patients with sarcopenia had a lower BMI, worse PS, and greater blood loss than did those without sarcopenia. In short, we show that sarcopenia has a detrimental effect on short-term outcomes in patients with ESCC. An association between sarcopenia and greater blood loss (as well as more pulmonary and other complications and longer hospital stays) has also been shown in patients with gastrointestinal cancer17).
The EWGSP and AWGS define sarcopenia as loss of muscle mass and strength and weak physical performance. Aging and cancer burden are risk factors for sarcopenia, as is the requirement for preoperative treatment in elderly patients and patients with advanced esophageal cancer. However, “true” sarcopenic patients are so physically unwell that they are excluded from routine major surgery. Therefore, the criteria for “surgical sarcopenia” (i.e., sarcopenia in patients undergoing surgery) should be defined according to postoperative risk.
In a previous study, the SMI significantly correlated with postoperative pneumonia after esophagectomy18). However, that report evaluated skeletal muscle mass only and did not consider grip strength or physical activity. Maeda et al.19) reported that the long-term prognosis of patients with ESCC was associated with skeletal muscle loss in the acute postoperative but not preoperative period.
In a meta-analysis of 29 studies with 3193 patients with esophageal cancer, the overall prevalence of sarcopenia, as determined via bioelectrical impedance analysis (623 patients, 10 studies) or other method, was 38% (range, 16–75%)20). However, that study did not include preoperative patients, and the prevalence of sarcopenia is likely higher in patients with advanced vs. early-stage cancer. In the present study, 10 patients (11%) were ASA PS class III or higher, and 36 patients (39%) had stage III/IV disease. The prevalence of sarcopenia was 20%, but may have been even lower because sarcopenia was diagnosed in patients who had muscle weakness or reduced physical function in addition to a low SMI. Nevertheless, and significantly, the sarcopenia group had a worse prognosis than did the non-sarcopenic group in terms of short-term OS.
In our study, nutritional status, as assessed using the PNI and mGPS, did not significantly affect short-term outcomes. In other studies, a lower PNI significantly correlated with preoperative skeletal muscle loss after pancreatoduodenectomy for pancreatic cancer, as did the female sex, older age, and a lower BMI21). In addition, the mGPS (as well PS and the CRP level) independently predicted OS in gastric and gastric junction cancer22). In contrast, and similar to our findings, neither the PNI nor mGPS was a significant factor in male patients23). Sarcopenia and malnutrition are closely related; however, because previous results regarding their relationship differ, more research is needed in the future. Prevention of muscle loss after surgery for esophageal cancer requires timely postoperative multidisciplinary treatments, such as nutritional and physical therapy, to prevent skeletal muscle loss24 25).
This study had two limitations. First, it was a retrospective, small-cohort study conducted at a single center. Second, postoperative outcomes were only observed for a short period. Studies with continuous long-term follow-up are needed. Also required are prospective interventional studies aimed at determining whether preoperative exercise and nutritional support programs improve postoperative outcomes in patients with sarcopenia.