Preoperative sarcopenia is a poor prognostic factor in lower rectal cancer patients undergoing neoadjuvant chemoradiotherapy: a retrospective study

This study aimed to investigate the effect of sarcopenia on the prognosis of advanced lower rectal cancer patients receiving neoadjuvant chemoradiotherapy (CRT). Sarcopenia has been recognized as an adverse factor for surgical outcomes in several malignancies. However, the impact of preoperative sarcopenia on rectal cancer patients receiving CRT is still unknown. This retrospective study included cT3-T4 anyN M0 lower rectal cancer patients who underwent CRT followed by R0 resection at our institution between October 2003 and December 2016. CRT consisted of 5-fluorouracil-based oral chemotherapy and long course radiation (50.4 Gy/28 fr). The psoas muscle area at the third lumbar vertebra level was evaluated by computed tomography before and after CRT, and was adjusted by the square of the height to obtain the psoas muscle mass index (PMI). Sarcopenia was defined as the sex-specific lowest quartile of the PMI. We assessed the association between pre- and post-CRT sarcopenia and postoperative prognosis. Among 234 patients, 55 and 179 patients were categorized as sarcopenia and non-sarcopenia patients, respectively. Although post-CRT sarcopenia correlated with residual tumor size, it had no association with other pathological features. The median follow-up period was 72.9 months, and the 5-year DFS and OS were 67.0% and 85.8%, respectively. Multivariate analysis showed that post-CRT sarcopenia was independently associated with poor DFS (HR: 1.76; P = 0.036), OS (HR: 2.01; P = 0.049), and recurrence in the liver (HR: 3.01; P = 0.025). Sarcopenia is a poor prognostic indicator in lower advanced rectal cancer patients treated with CRT.