LAUSR

We read with interest the article by Matsui et al. [1] published recently in your journal. We congratulate these authors for highlighting the impact of preoperative grip strength, indicative of sarcopenia, on surgery for advanced gastric cancer. Herewith, we present the following remarks. First, the term “sarcopenia” is being used inappropriately in some cancer studies to mean “age-related loss of muscle mass” [2]. However, in 2010, its definition evolved to “age-related loss of muscle mass and muscle function” [2]. It is noteworthy that muscle function, as strength and performance, predicts adverse outcomes more accurately and is crucial to the diagnosis of sarcopenia [2]. Although the authors measured both muscle mass and function (as grip strength), they diagnosed sarcopenia somewhat erroneously according to only muscle mass measurements [1]. Second, muscle mass and function vary according to age, gender, height, and weight [3]. Therefore, although these factors did not reach their statistical threshold (p < 0.10), together with age, they should be added to the multivariate analyses to eliminate their effects. Furthermore, the authors did not use absolute values for age, body mass index, and grip strength. What is the rationale for categorizing all variables? Cut-off values were used to calculate low skeletal muscle mass index and grip strength according to ROC analyses; however, there are well-established methods for cut-off values in the literature, whereby two standard deviations below the healthy young adult values are used for both parameters [2]. Third, grip strength is a simple and cheap screening tool, and a powerful predictor of future morbidity and mortality [4]. As such, with the potential to serve as a “vital sign” for middle-aged and older adults, it provides a marker of neuromusculoskeletal integrity and health in general, and of sarcopenia in particular [4]. Accordingly, measuring grip strength would be a better predictor of neuromusculoskeletal ageing and frailty over chronological ageing. If the person has low grip strength but normal muscle mass (dynapenia), other causes affecting the neuromotor control such as cognitive impairment, movement, balance, and mood disorders should be considered [5]. In conclusion, we underscore the value of grip strength as a simple but vital test, but when used together with muscle mass assessment, for the diagnosis of sarcopenia. Only through this can the effect of sarcopenia (or dynapenia) be evaluated accurately in cancer patients.