The impact of sarcopenia on pathologic complete response following neoadjuvant chemoradiation in rectal cancer.

PURPOSE: The role of sarcopenia in pathologic complete response (pCR) following neoadjuvant chemoradiotherapy (nCRT) in non-metastatic locally advanced rectal cancer is currently unknown. The present study investigates the association between sarcopenia and post-nCRT pCR. METHODS: The data of patients operated on following nCRT between January 2013 and January 2020 were collected retrospectively. Sarcopenia was diagnosed based on the calculation of the skeletal muscle index (SMI) from computed tomography carried out at the time of the initial diagnosis. A statistical analysis was then conducted for predictors of pCR. RESULTS: The study included 61 patients with an average age of 57.3 years, 28 of whom formed the non-sarcopenic group (NSG) and 33 the sarcopenic group (SG). Of the patients, 32.7% were at clinical stage 2, and 67.3% were at clinical stage 3. Pathologic data following a mesorectal excision revealed a pCR rate of 21.4% in the NSG compared with 3% in the SG, which was a statistically significant difference (p = 0.025). The TNM downstaging rate was higher in the NSG than in the SG, although the difference was not statistically significant (50% vs. 33.3%, p = 0.28). A univariate analysis revealed the factors affecting pCR to be non-sarcopenia (p = 0.025), age < 61 years (p = 0.004), interval to surgery ≥ 8 weeks (p = 0.029), and serum CEA < 2.5 ng/ml (p = 0.035). CONCLUSION: Sarcopenia was found to be a negative marker of pCR following nCRT in non-metastatic locally advanced rectal cancer.