直肠癌肿瘤直径影响因素的广义相加模型分析

The influential factors on tumor diameters in rectal cancer analyzed with generalized additive model

目的探索直肠癌患者肿瘤直径的影响因素。方法收集直肠癌根治术的横断面研究数据,按肿瘤直径的中位数分组,比较组间临床病理特征差异。局部加权回归散点平滑方法(LOWESS)分析肿瘤直径与连续变量之间的关系。广义相加模型(GAM)进一步分析肿瘤直径的关联因素。结果直肠癌患者分为肿瘤直径<4 cm和≥4 cm组,组间T分期(P<0.01)、TNM分期(P<0.05)的差异有统计学意义;≥4 cm组癌胚抗原(CEA)的中位数[4.90 ng/ml,四分位间距(2.39,9.53)]高于<4 cm组[2.93 ng/ml,四分位间距(1.78,4.90)],差异有统计学意义(P<0.01)。LOWESS分析发现,年龄、距肛缘的距离、CEA、中性粒细胞、淋巴细胞、血小板、中性粒细胞淋巴细胞比值、血小板淋巴细胞比值与肿瘤直径存在非线性关系。GAM结果显示,血小板增加(P<0.05)、T分期越晚(P<0.01),肿瘤直径越大;CEA升高与肿瘤直径增大有关(P<0.01),存在饱和效应。结论血小板、T分期、CEA与直肠癌的肿瘤直径存在关联关系,有助于对直肠癌肿瘤直径影响因素的研究。

Objective To explore the influential factors on tumor diameters in rectal cancer.Methods Cross sectional study data were collected from patients undergoing radical resection of rectal cancer.Patients were grouped by median value of tumor diameter,and the clinical pathological characteristics were compared between the two groups.The associations between tumor diameter and continuous variables were analyzed using locally weighted scatterplot smoothing(LOWESS)method.The associating factors of tumor diameter were further analyzed using generalized additive model(GAM).Results Patients with rectal cancer were divided into two groups with tumor diameter either<4 centimeters or≥4 centimeters.Proportions of T,TNM stages differed significantly between different groups.Median carcinoembryonic antigen(CEA)in≥4 centimeters group were 4.90 ng/ml(inter-quartile range[IQR]2.39,9.53 ng/ml),much higher than that in<4 centimeters group(2.93 ng/ml[IQR:1.78,4.90 ng/ml]),P<0.01.LOWESS analysis showed that there were non-linear relationships between tumor diameter and the following variables:age,the distance between tumor and anal verge,CEA,neutrophils,lymphocytes,platelets,neutrophil-to-lymphocyte ratio,and platelet-to-lymphocyte ratio.GAM showed that increased blood platelets(P<0.05)and later T stage(P<0.01)were significantly associated with increased tumor diameters,and increased CEA levels were also associated with larger tumors(P<0.01),but there were saturation effects.Conclusion Platelets,T stage and CEA are associated with tumor diameter in rectal cancer,indicating that the above factors should be considered when studying associated factors of tumor diameter in rectal cancer.