Changes in psoas muscle area in patients with colorectal cancer three years after surgery: a longitudinal approach

The purpose of this study was to investigate long-term changes in psoas muscle area after colorectal cancer (CRC) surgery and their association with preoperative clinical characteristics and mortality. Skeletal muscle loss predicts poor CRC outcomes, but evidence on postoperative changes is limited. We included 272 patients with localized CRC who underwent elective surgery at Herlev Hospital, Denmark, between 2014 and 2019. Computed tomography (CT) scans before surgery and at three-year follow-up were used to assess psoas muscle area at the L3 vertebral level. Change in muscle area was categorized as > 5% decrease, no change, or > 5% increase. Associations between preoperative clinical characteristics and mortality were analyzed in relation to muscle change. At three-year follow-up after surgery, 39% of patients showed a > 5% decrease in psoas muscle area, 33% had no change, and 28% had a > 5% increase. The results demonstrated that both Union for International Cancer Control (UICC) tumor stage and receipt of adjuvant chemotherapy were independently associated with postoperative changes in psoas muscle area. Among patients who did not receive adjuvant chemotherapy, age was associated with muscle area change, whereas no preoperative clinical characteristics were associated with muscle area change among those receiving adjuvant chemotherapy. Importantly, postoperative longitudinal changes in psoas muscle area were not associated with overall mortality. A considerable proportion of patients with CRC experience long-term loss of psoas muscle area following surgery. These results underscore the variability in postoperative muscle changes and highlight the need for further research to identify high-risk subgroups.