Muscle wasting and survival following pre-operative chemoradiotherapy for locally advanced rectal carcinoma

Background & aims: Neoadjuvant chemoradiotherapy (NACRT) has increased local control in locally advanced rectal cancer. Reduced skeletal muscle mass (sarcopenia), or ongoing muscle wasting, is associated with decreased survival in cancer. This study aims to assess the change in body composition during NACRT and its impact on outcome using computed tomography (CT) imaging in locally advancedrectal cancer (LARC) patients.

Methods: LARC patients treated with NACRT were selected from a prospectively maintained database and retrospectively analyzed. One-hundred twenty-two patients who received treatment between 2004 and 2012 with available diagnostic CT imaging obtained before and after NACRT were identified. Cross-sectional areas for skeletal muscle was determined, and subsequently normalized for patient height. Differences between skeletal muscle areas before and after NACRT were computed, and their influenceon overall and disease-free survival was assessed.

Results: A wide distribution in change of body composition was observed. Loss of skeletal muscle mass during chemoradiotherapy was independently associated with disease-free survival (HR0.971; 95% CI:0.946e0.996; p¼0.025) and distant metastasis-free survival (HR0.942; 95% CI: 0.898e0.988; p¼0.013).No relation was observed with overall survival in the current cohort.

Conclusions:Loss of skeletal muscle mass during NACRT in rectal cancer patients is an independent prognostic factor for disease-free survival and distant metastasis-free survival following curative intentresection.