Serum myostatin and IGF-I status in cancer patients with and without cachexia

Introduction. Cancer cachexia is a syndrome that includes weight loss, anorexia, loss of skeletal muscle, and fat and results in a lowered quality of life and survival rate for cancer patients. The mechanism of cachexia is often unclear.;Purpose. The purpose of this study was to compare serum myostatin and IGF-I levels in men and women with cancer cachexia (WL), with cancer but without cachexia (C), and in an age-matched, healthy control group (HC) in order to determine if serum myostatin and IGF-I are possibly correlated with cancer associated weight loss. A secondary purpose was to determine if myostatin and IGF-I are correlated with body composition variables in cancer patients.;Methods. Subjects were split into one of three groups including a healthy age-matched control group (n=11), a group of weight stable cancer patients (n=10) and a group of cancer patients (n=10) who had lost at least 10% of their pre-diagnosis normal weight. Subjects filled out health history, the European Prospective Investigation into Cancer (EPIC) research tool for physical activity (Epaq2), a quality of life questionnaire (European Organization for Research and Treatment of Cancer scale, EORTC) and medical treatment history. Serum was analyzed and quantified for myostatin by western blot protocol and IGF-I by immunoradiometric assay (IRMA). The subjects had bone mineral content assessed via dual energy x-ray absorptiometry (DXA), body density assessed via air displacement plethysmography (Bod Pod) and total, intracellular and extracellular body water measured with a bioimpedance spectrum (BIS) analyzer. The four component model was used to estimate percent body fat.;Results. There were no significant differences (p>0.05) in physical characteristics between groups except in the percentage of weight loss from normal pre-diagnosis weight with WL showing more loss than C and HC and having a mean loss of 20.46 kg (p<0.01). Body composition variables were also not significantly different between the groups with the exception of intra-cellular fluid being significantly lower (p<.01) in WL than in HC. Myostatin and IGF-I levels were not significantly different between the groups. Myostatin had a significant positive correlation with METs per week at r=.697 (p=.03) in WL. MET stands for "metabolic equivalent" and is defined as the ratio of the work metabolic rate to the resting metabolic rate3. One (1) MET is the rate at which adults burn kcal at rest: This is approximately 1 kcal per kilogram of body weight per hour (expressed as 1 kcal/kg/hr). The correlation between METs and myostatin may be the result of myostatin production being stimulated by glucocorticoid release at higher levels of activity. IGF-I did show a positive correlation to the percentage of weight change from normal weight in WL of r=.710 (p=.02), indicating the relationship of higher IGF-I concentrations to lower amounts of weight loss. Finally, there were significant differences between WL and HC when examining the quality of life questionnaires. WL scored significantly higher (p<.05) than HC on the symptoms scale and significantly lower (p<.05) than HC on the global health status and functional scales, indicating lower functional capacity and more difficulty with activities of daily living by WL.;Conclusions. The groups have similar IGF-1 and myostatin concentrations suggesting that these hormones are not the mechanism through which weight is altered in cancer patients with cachexia. The weight loss group showed a significant positive correlation between IGF-1 concentrations and the amount of weight change from normal which indicates that increased IGF-1 levels may be beneficial in the weight loss group and may help to attenuate the weight loss in this group.