Sarcopenia and Gynecologic Malignancy
To investigate the correlation of sarcopenia with prognostic factors in patients with cervical cancer undergoing concurrent chemoradiotherapy, Dr Kiyotoki and colleagues1 conducted a retrospective trial. In this current work,1 they reported that sarcopenia served as a poor recurrence and survival, in patients with cervical cancer undergoing concurrent chemoradiotherapy. Not limited to this study, prognostic importance of sarcopenia has been increasingly evaluated in gynecologic malignancy.2 However, generality of the results of the medical studies is one of the key factors that are particularly related to define the medical condition in a way wisely accepted by general authorities. So, we would like to focus on the methodology of the article by Dr Kiyotoki and colleagues.
Since the first definition of sarcopenia was introduced by Irwin Rosenberg in 1989, various definition of sarcopenia has been generated by expert groups.3 Finally, in 2010, the European Working Group on Sarcopenia in Older People (EWGSOP)3 proposed new and widely accepted sarcopenia definition, based on measurement of muscle mass and function. In view of EWGSOP's definition, the article by Dr Kiyotoki and colleagues has a critical limitation because they did not evaluate muscle function and classified patients solely as sarcopenic because of muscle mass measurement.
Another critical point we would like to comment on in the study Dr Kiyotoki and colleagues is the technique of muscle measurement. EWGSOP advised to use several techniques including computed tomography (CT) and magnetic resonance imaging, dual-energy x-ray absorptiometry, and bioelectrical impedance analysis.3 By these, full-body CT and magnetic resonance imaging are criterion-standard techniques, and dual-energy x-ray absorptiometry and bioelectrical impedance analysis are validated alternatives.3 To the best of our knowledge, single-slice CT analysis at the level of the third lumbar vertebra, used in the study by Dr Kiyotoki and colleagues,1 has not been validated against the criterion standard. This point is extremely critical because reproducibility and validity of the results are mainly related to the validity of methodology. Thus, we suppose that the results obtained here might have been confounded by the methodology.