Abstract：Objective To investigate the value of circulating tumor (ct) DNA in predicting pathological complete remission (pCR) of neoadjuvant chemoradiotherapy (nCRT) in patients with locally advanced rectal cancer (LARC). Methods A total of 104 LARC patients recruited from March 2020 to September 2021 were selected as the study objects, and the baseline data and plasma samples during nCRT were collected for gene sequencing. The association between ctDNA status and treatment response was analyzed. The value of ctDNA alone, MRI alone, and the combination of ctDNA and MRI in predictive pCR was evaluated. The independent clinical factors influencing pCR were analyzed by logistic univariate and multifactorial analysis. Results Of the 104 patients, 35 (33.65%) achieved pCR after surgery, and 91 (87.50%) had positive ctDNA at baseline. The proportion of negative ctDNA and ctDNA clearance before surgery in patients with pCR were significantly higher than those in patients with N-pCR (P＜0.05).The proportion of ctDNA negativity and ctDNA clearance in pTRG3 patients were significantly reduced (P＜0.05). Logistic univariate and multivariate analysis showed that ctDNA clearance and cCR were independent clinical factors affecting pCR (P＜0.05). The area under the pCR curve of ctDNA clearance combined with MRI diagnosis was 0.937 (0.885-0.989), which was higher than that of ctDNA clearance or MRI alone. Conclusions The standard of clinical complete response based on MRI combined with ctDNA has the value of predicting pCR in LARC patients.
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2024, Vol. 35 
