直肠癌是消化道最常见的恶性肿瘤之一,其发病率呈逐年上升的趋势,约占全身恶性肿瘤的15%以上[1]。直肠癌的主要治疗方法是手术切除,有资料显示Ⅰ期直肠癌手术治愈率可达90%~95%以上,Ⅱ、Ⅲ、Ⅳ期的术后5年生存率分别为64%~78%、27%~33%和5%~14%[2]。准确的术前诊断及术前分期对 Rectal cancer is one of the most common malignant tumors of the digestive tract, and its incidence has been increasing year by year, accounting for more than 15% of systemic malignancies [1]. The main treatment for rectal cancer is surgical resection. Data show that the surgical cure rate of stage Ⅰ rectal cancer can reach 90% -95%. The 5-year postoperative survival rates of stage Ⅱ, Ⅲ and Ⅳ are 64% -78% 27% ~ 33% and 5% ~ 14% [2]. Accurate preoperative diagnosis and preoperative staging