Objective To investigate the characteristics of No.253 lymph node metastasis in middle and low rectal cancer and its influencing factors.

Methods The retrospective case-control study was conducted. The clinicopathological data of 2 316 patients with middle and low rectal cancer who were admitted to the First Affiliated Hospital of Nanjing Medical University from January 2013 to October 2021 were collected. There were 1 339 males and 977 females, aged (61±12)years. All patients underwent D₃ radical surgery for rectal cancer. Observation indicators: (1) No.253 lymph node metastasis in patients with middle and low rectal cancer; (2) analysis of influencing factors for No.253 lymph node metastasis in patients with middle and low rectal cancer. Measurement data with normal distribution were represented as Mean±SD. Count data were expressed as absolute numbers and percentages, and comparison between groups was performed by the chi‑square test. Logistic regression model was used for multivariate analysis.

Results (1) No.253 lymph node metastasis in patients with middle and low rectal cancer. There were 128 of 2 316 patients with positive No.253 lymph node and 2 188 cases with negative No.253 lymph node. The No.253 lymph node metastasis rate was 5.527%(128/2 316). There were 568 of 2 316 patients with the distance from distal margin of tumor to anal margin as 8‒10 cm, 766 cases as ≥6 cm and<8 cm, 982 cases as <6 cm. Of the 568 patients with the distance from distal margin of tumor to anal margin as 8‒10 cm, 57 cases had positive No.253 lymph node, including 3 cases(5.263%) of high differentiated tumor, 9 cases(15.789%) of moderate differentiated tumor, 45 cases(78.948%) of low differentiated tumor, respectively. There was 0 case of the above 57 patients with positive No.253 lymph node in TNM stage Ⅰ, 0 case in TNM stage Ⅱ, 20 cases(35.088%) in TNM stage Ⅲ, 37 cases(64.912%) in TNM stage Ⅳ, respectively. Of the 766 patients with the distance from distal margin of tumor to anal margin as ≥6 cm and <8 cm, 42 cases had positive No.253 lymph node, including 4 cases(9.524%) of high differentiated tumor, 11 cases(26.190%) of moderate differentiated tumor, 27 cases(64.286%) of low differentiated tumor, respectively. There was 0 case of the above 42 patients with positive No.253 lymph node in TNM stage Ⅰ, 0 case in TNM stage Ⅱ, 19 cases(45.238%) in TNM stage Ⅲ, 23 cases(54.762%) in TNM stage Ⅳ, respectively. Of the 982 patients with the distance from distal margin of tumor to anal margin as <6 cm, 29 cases had positive No.253 lymph node, including 1 case (3.448%) of high differentiated tumor, 3 cases (10.345%) of moderate differentiated tumor, 25 cases (86.207%) of low differentiated tumor, respectively. There was 0 case of the above 29 patients with positive No.253 lymph node in TNM stage Ⅰ, 0 case in TNM stage Ⅱ, 12 cases(41.379%) in TNM stage Ⅲ, 17 cases(58.621%) in TNM stage Ⅳ, respectively. (2) Analysis of influencing factors for No.253 lymph node metastasis in patients with middle and low rectal cancer. Results of univariate analysis showed that tumor T staging, tumor N staging, tumor TNM staging, tumor differentiation degree, the distance from distal margin of tumor to anal margin were related factors for No.253 lymph node metastasis in patients with middle and low rectal cancer (χ²=28.48, 44.58, 172.62, 227.67, 34.57, P<0.05). Results of multivariate analysis showed that tumor T staging as stage T4, tumor N staging as stage N2, tumor TNM staging as stage Ⅳ, low differentiated tumor, the distance from distal margin of tumor to anal margin as ≥6 cm and <8 cm, 8‒10 cm were independent risk factors for No.253 lymph node metastasis in patients with middle and low rectal cancer (odds ratio=2.74, 3.48, 10.72, 21.47, 1.92, 3.67, 95% confidence intervals as 1.91‒3.92, 2.42‒4.98, 7.36‒15.62, 10.33‒44.60, 1.27‒2.91, 2.31‒5.81, P<0.05).

Conclusions The risk of No.253 lymph node metastasis is relatively high in middle and low rectal cancer patients with long distance from distal margin of tumor to anal margin, low differentiated tumor, and in high TNM stages. Tumor T staging as stage T4, tumor N staging as stage N2, tumor TNM staging as stage Ⅳ, low differentiated tumor, the distance from distal margin of tumor to anal margin as ≥6 cm and <8 cm, 8‒10 cm are independent risk factors for No.253 lymph node metastasis in patients with middle and low rectal cancer.