Association between body composition and recurrence in stage II-III colon cancer: a retrospective cohort study

Colorectal Cancer (CRC) is a common cause of cancer death and prognostic factors are used to determine management. Patients with advanced disease often become cachectic, losing skeletal muscle mass and density, as well as subcutaneous fat. CT can be used to assess body composition by measuring skeletal muscle area, density and subcutaneous and visceral fat. We hypothesise that evidence of sarcopenia or myosteatosis at diagnosis is associated with an increased risk of cancer recurrence.

Patients discussed at the CRC multidisciplinary team meeting between 2015-2021 at a single institution were collated prospectively. We retrospectively gathered patient information, tumour characteristics and initial CT staging scans. Patients with stage II-III colon cancer were included. Patients with rectal cancer and those who underwent neoadjuvant therapy were excluded. We analysed CT images at the level of the L3 transverse processes using pre-specified criteria with a machine learning model (Mosamatic) to determine body composition. Pre-defined definitions of sarcopenia and myosteatosis were taken from the literature. The primary outcome assessed was recurrence-free survival (RFS).

615 patients with stage II-III colon cancer underwent surgery and 120 developed a recurrence. Skeletal muscle radiation attenuation was lower in patients with recurrence (34.3 HU vs 32.2 HU, p = 0.012) but there was no significant difference in Skeletal Muscle Index (44.2cm²/m² vs 42.2 cm²/m², p=0.124). 71.7% of patients who developed recurrence had myosteatosis in comparison to 54.9% in the no recurrence group (p=0.001). At 1-year the RFS was 92.0% (95% CI, 88.7-95.4) in the normal group and 88.3% (95% CI, 84.9-91.7) for those with myosteatosis; but at 5-years the RFS was 86.2% (95% CI, 82.0-90.6) in the normal group and 74.6% (95% CI, 70.0-79.4) in the myosteatosis group (p<0.001). Myosteatosis was an independent predictor of recurrence on multivariate analysis (HR=1.62, p=0.026). There was no difference in RFS looking at sarcopenia alone. At 1-year RFS was 92.0% (95% CI, 88.7-95.3) in the normal group and 88.2% (95% CI, 84.8-91.7) in the sarcopenic group; at 5-years RFS was 81.9% (95% CI, 77.3-86.8) in the normal group and 77.5% (95% CI, 73.1-82.2) in the sarcopenic group (p=0.17).

Myosteatosis was associated with increased risk of recurrence in our cohort. This could be a useful prognostic factor in colon cancer and should be validated in prospective studies.