To evaluate the impact of age on the efficacy of neoadjuvant chemoradiotherapy (NCRT) in patients with locally advanced rectal cancer (LARC). LARC patients undergoing NCRT and radical surgery from 2011 to 2018 were divided into young (< 40 years) and old (≥40 years) groups. Multivariate analyses were performed to identify predictive factors for pathological complete response (pCR). Predictive nomograms and decision curve analysis were used to compare the models including/excluding age groups. Immunohistochemical analysis was performed to detect CD133 expression in LARC patients. A total of 901 LARC patients were analyzed. The young group was associated with poorly differentiated tumors, more metastatic lymph nodes, higher perineural invasion, and a lower tumor regression grade (P = 0.008; P < 0.001; P < 0.001; P = 0.003). Logistic regression analysis demonstrated that age < 40 years (HR = 2.190, P = 0.044), tumor size (HR = 0.538, P < 0.001), pre-NCRT cN stage (HR = 0.570, P = 0.036), and post-NCRT CEA level (HR = 0.877, P = 0.001) were significantly associated with pCR. Predictive nomograms and decision curve analysis demonstrated that the predictive ability of models including the age group was superior to that of models excluding the age group. Higher CD133 expression was more common in young LARC patients. Young patients with LARC were associated with lower pCR rates following NCRT. The ability of the predictive model was greater when based on the age group. Young LARC patients were associated with a higher CD133+ tumor stem cell burden, which contributed to the lower pCR rates.

中文翻译：

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年轻的局部晚期直肠癌患者对新辅助放化疗的治疗反应更差。

评估年龄对局部晚期直肠癌（LARC）患者新辅助放化疗（NCRT）疗效的影响。从2011年至2018年接受NCRT和根治性手术的LARC患者分为年轻组（<40岁）和老年组（≥40岁）。进行多变量分析以鉴定病理完全缓解（pCR）的预测因素。使用预测列线图和决策曲线分析来比较包括/不包括年龄组的模型。进行免疫组织化学分析以检测LARC患者中的CD133表达。总共分析了901名LARC患者。年轻组与分化差的肿瘤，更多的淋巴结转移，更高的神经周浸润和更低的肿瘤消退等级相关（P = 0.008； P <0.001； P <0.001； P = 0.003）。Logistic回归分析显示年龄<40岁（HR = 2.190，P = 0.044），肿瘤大小（HR = 0.538，P <0.001），NCRT前cN分期（HR = 0.570，P = 0.036）和NCRT后CEA水平（HR = 0.877，P = 0.001）与pCR显着相关。预测列线图和决策曲线分析表明，包括年龄组的模型的预测能力优于不包括年龄组的模型的预测能力。较高的CD133表达在年轻的LARC患者中更为常见。年轻的LARC患者在NCRT后与较低的pCR率相关。当基于年龄组时，预测模型的能力更大。年轻的LARC患者与较高的CD133 +肿瘤干细胞负担相关，这导致较低的pCR率。肿瘤大小（HR = 0.538，P <0.001），NCRT前cN分期（HR = 0.570，P = 0.036）和NCRT后CEA水平（HR = 0.877，P = 0.001）与pCR显着相关。预测列线图和决策曲线分析表明，包括年龄组的模型的预测能力优于不包括年龄组的模型的预测能力。较高的CD133表达在年轻的LARC患者中更为常见。年轻的LARC患者在NCRT后与较低的pCR率相关。当基于年龄组时，预测模型的能力更大。年轻的LARC患者与较高的CD133 +肿瘤干细胞负担相关，这导致较低的pCR率。肿瘤大小（HR = 0.538，P <0.001），NCRT前cN分期（HR = 0.570，P = 0.036）和NCRT后CEA水平（HR = 0.877，P = 0.001）与pCR显着相关。预测列线图和决策曲线分析表明，包括年龄组的模型的预测能力优于不包括年龄组的模型的预测能力。较高的CD133表达在年轻的LARC患者中更为常见。年轻的LARC患者在NCRT后与较低的pCR率相关。当基于年龄组时，预测模型的能力更大。年轻的LARC患者与较高的CD133 +肿瘤干细胞负担相关，这导致较低的pCR率。预测列线图和决策曲线分析表明，包括年龄组的模型的预测能力优于不包括年龄组的模型的预测能力。较高的CD133表达在年轻的LARC患者中更为常见。年轻的LARC患者在NCRT后与较低的pCR率相关。当基于年龄组时，预测模型的能力更大。年轻的LARC患者与较高的CD133 +肿瘤干细胞负担相关，这导致较低的pCR率。预测列线图和决策曲线分析表明，包括年龄组的模型的预测能力优于不包括年龄组的模型的预测能力。较高的CD133表达在年轻的LARC患者中更为常见。年轻的LARC患者在NCRT后与较低的pCR率相关。当基于年龄组时，预测模型的能力更大。年轻的LARC患者与较高的CD133 +肿瘤干细胞负担相关，这导致较低的pCR率。当基于年龄组时，预测模型的能力更大。年轻的LARC患者与较高的CD133 +肿瘤干细胞负担相关，这导致较低的pCR率。当基于年龄组时，预测模型的能力更大。年轻的LARC患者与较高的CD133 +肿瘤干细胞负担相关，这导致较低的pCR率。