Page 103 - Risk quantification and modification in older patients with colorectal cancer

Physical performance and poor surgical outcomes
skeletal muscle mass in combination with decreased physical performance and postoperative complications, earlier studies in CRC patients showed associations with increased risk of sepsis and severe complications.9, 5
That muscle mass was unrelated to postoperative complications is in line with a study in older Asian CRC patients (>65 years)25 and a recent study in older Dutch CRC patients.26 In addition, our study findings correlate with previous findings that muscle density is more strongly associated with surgical outcome compared to skeletal muscle mass.6,24,25 Studies investigating the association between low skeletal muscle mass and density and OS are inconsistent. Van Vught et al. also found no association.27 However, an association was reported by studies that included younger and older patients, including those with metastatic disease2-4,7,28 or only open surgery.6
The lack of association found in our cohort between skeletal muscle mass and outcomes compared to the studies mentioned above could have several explanations. Our study population consisted of only older patients and patients with elective surgery for stage I-III disease in contrast to the before-mentioned studies. In this group, low skeletal muscle mass can be assumed to be part of the chronological ageing process and less likely as a result of secondary causes such as cancer. Also, this selection resulted in less variety in skeletal muscle mass and density, limiting its discriminative power. We used sex-specific quartiles for skeletal muscle mass and density in our cohort to overcome this problem. Another explanation is that in studies of patients with advanced disease, skeletal muscle mass may have declined due to the presence of metastasis. Moreover, skeletal muscle mass measurements are only normalised for stature. As a consequence, low skeletal muscle mass is underestimated in overweight patients and overestimated in underweight patients. Patients with preserved adipose tissue despite decreased muscle mass (sarcopenic obesity), may represent a separate risk group.6,29,30 Hence, with muscle density, the amount of fat infiltration is accounted for, and this may explain the importance of skeletal muscle density over skeletal muscle mass.
In non-metastatic CRC patients, physical performance measures such as preoperative use of a mobility aid alone, are unlikely to change a surgical treatment plan. However, as a predictor in risk models for outcomes of CRC surgery, mobility aid use might be useful.31,32 In addition, low physical performance could serve
101
5