Longitudinal Changes in CT Body Composition in Patients Undergoing Surgery for Colorectal Cancer and Associations With Peri-Operative Clinicopathological Characteristics

Abstract

There is evidence for the direct association between body composition, the magnitude of the systemic inflammatory response, and outcomes in patients with colorectal cancer. Patients with a primary operable disease with and without follow-up CT scans were examined in this study. CT scans were used to define the presence and changes in subcutaneous fat, visceral fat, skeletal muscle mass, and skeletal muscle density (SMD). In total, 804 patients had follow-up scans and 83 patients did not. Furthermore, 783 (97%) patients with follow-up scans and 60 (72%) patients without follow-up scans were alive at 1 year. Patients with follow-up scans were younger (p < 0.001), had a lower American Society of Anaesthesiology Grade (p < 0.01), underwent a laparoscopic surgery (p < 0.05), had a higher BMI (p < 0.05), a higher skeletal muscle index (SMI) (p < 0.01), a higher SMD (p < 0.01), and a better 1-year survival (p < 0.001). Overall only 20% of the patients showed changes in their SMI (n = 161) and an even lower percentage of patients showed relative changes of 10% (n = 82) or more. In conclusion, over the period of ~12 months, a low-skeletal muscle mass was associated with a systemic inflammatory response and was largely maintained following surgical resection.

Keywords: TNM; body composition; colorecal cancer; computer tomograph; glasgow prognostic score; systemic inflammation.

Figure 1

Prisma diagram of patients excluded from the study due to missing clinicopathological data, blood tests, or death within 1 month of surgery. Further subdivisions showing the number of patients with follow-up scans at 1 year and patients alive at 1 year.

Figure 2

Example of selection of CT body composition—fat areas using ImageJ software; (A) mid-L3 vertebra axial slice from preoperative portal venous phase CT, (B) threshold selection of adipose tissue using automatic selection of pixels of radiodensity ranging −190 to −30 Hounsfield units (HU); (C) region of interest (ROI) selection for total fat area (TFA, cm²); and (D) ROI selection for visceral fat area (VFA, cm²). Adapted from McSorley et al. (22).

Figure 3

Example of selection of CT body composition—skeletal muscle area (SMA) using ImageJ software; (A) mid-L3 vertebra axial slice from preoperative portal venous phase CT; (B) threshold selection of skeletal muscle tissue using automatic selection of pixels of radiodensity ranging _29–150 Hounsfield units (HU); (C) region of interest (ROI) selection for SMA (cm²). Adapted from McSorley et al. (22).

Figure 4

The relationship between change in SMI on follow-up and overall survival (n = 804, p < 0.001) over a 36-month follow-up period.

Figure 5

(A) Percentage change in subcutaneous fat index (SFI) in patients <74 years of age (n = 596). (B) Percentage change in SFI in patients >74 years of age (n = 208). Comparison of percentage change in SFI in patients <74 years (n = 596) and >74 years of age (n = 208) (p = 0.922). (C) Percentage change in visceral fat area (VFA) in patients <74 years of age (n = 596). (D) Percentage change in VFA in patients >74 years of age (n = 208). Comparison of percentage change in VFA in patients <74 years (n = 596) and >74 years of age (n = 208) (p = 0.171). (E) Percentage change in skeletal muscle index (SMI) in patients <74 years of age (n = 596). (F) Percentage change in SMI in patients >74 years of age (n = 208). Comparison of percentage change in SMI in patients <74 (n = 596) and >74 years of age (n = 208) (p = 0.197). (G) Percentage change in skeletal muscle density (SMD) in patients <74 years of age (n = 596). (H) Percentage change in SMD in patients >74 years of age (n = 208). Comparison of percentage change in SMI in patients <74 years (n = 596) and >74 years of age (n = 208) (p = 0.721).

Figure 6

(A) Percentage change in SFI in female patients (n = 359). (B) Percentage change in SFI in male patients (n = 445). Comparison of percentage change in SFI in female (n = 359) and male (n = 445) patients (p = 0.380). (C) Percentage change in VFA in female patients (n = 359). (D) Percentage change in VFA in male patients (n = 445). Comparison of percentage change in VFA in female (n = 359) and male (n = 445) patients (p = 0.04). (E) Percentage change in SMI in female patients (n = 359). (F) Percentage change in SMI in male patients (n = 445). Comparison of percentage change in SMI in female (n = 359) and male (n = 445) patients (p = 0.324). (G) Percentage change in SMD in female patients (n = 359). (H) Percentage change in SMD in male patients (n = 445). Comparison of percentage change in SFD in female (n = 359) and male (n = 445) patients (p = 0.089).

Figure 7

(A) Percentage change in SFI in patients with a mGPS 0 (n = 600). (B) Percentage change in SFI in patients with a mGPS 1 or 2 (n = 204). Comparison of percentage change in SFI in mGPS 0 (n = 600) and mGPS 1 or 2 (n = 204) patients (p < 0.001). (C) Percentage change in VFA in patients with a mGPS 0 (n = 600). (D) Percentage change in VFA in patients with a mGPS 1 or 2 (n = 204). Comparison of percentage change in VFA in mGPS 0 (n = 600) and mGPS 1 or 2 (n = 204) patients (p = 0.614). (E) Percentage change in SMI in patients with a mGPS 0 (n = 600). (F) Percentage change in SMI in patients with a mGPS 1 or 2 (n = 204). Comparison of percentage change in SMI in mGPS 0 (n = 600) and mGPS 1 or 2 (n = 204) patients (p = 0.002). (G) Percentage change in SMD in patients with a mGPS 0 (n = 600). (H) Percentage change in SMD in patients with a mGPS 1 or 2 (n = 204). Comparison of percentage change in SMD in mGPS 0 (n = 600) and mGPS 1 or 2 (n = 204) patients (p = 0.289).