Sarcopenia Is a Condition With Increasing Importance in Medical Oncology.

Sarcopenia has increasingly been proposed as a predictor of response to treatment in oncology patients. In the August 2015 issue of , Arrieta et al. reported that routinely screening for sarcopenia and nutritional status was helpful in determining the next step of chemotherapy as well as toxicities in patients with non-small cell lung cancer [1]. The authors specifically addressed the association of sarcopenia with afatinib-related gastrointestinal toxicity as an adverse effect. However, the results in this work seem to require some more discussion.

In the study by Arrieta et al. [1], sarcopenia was assessed by computed tomography (L3 muscle index) based on the knowledge that it has high correlation with whole-body skeletal muscle mass. First, muscle mass estimation with computed tomography is a valuable option but it is not enough to identify sarcopenia correctly because the diagnosis of sarcopenia needs to be supported by clinical and laboratory measurements. Impaired muscle function and strength, which have gained significant importance in recent years, are also important components of sarcopenia according to a consensus report from the European Working Group on Sarcopenia in Older People [2, 3]. The group addressed not only muscle mass but also physical performance as assessed by gait speed, and grip strength measured by handheld dynamometer, to be used in an algorithmic workup to decide on the presence or absence of sarcopenia. Second, the fixed wide ranges of attenuation values for defining muscle mass area in the study by Arrieta et al. remain relatively broad, which can lead to false distinction of tissues [4]. Moreover, the fixed wide ranges of attenuation make it harder to differentiate between presarcopenia and sarcopenia. To sum up, although a decrease in muscle mass was detected in 68.8% of the participants, it is not actually evident what proportion the patients had true sarcopenia. Clarification of these issues may be relevant to the study results.