Clinical characteristics and predictive factors of pathological lateral pelvic lymph node metastasis in patients with rectal cancer.

In recent years, selective lateral lymph node dissection (LLND) has been performed more frequently. The present study aimed to explore the clinical characteristics and predictive factors of pathological lateral pelvic lymph node metastasis (LPLNM), which may be helpful for pre-treatment decisions. The present study included 64 patients with rectal cancer and clinically suspected LPLNM who underwent total mesorectal excision (TME) and LLND between February 2019 and April 2024. According to pathological outcomes, the patients were divided into the negative LPLN (n=40) and positive LPLN (n=24) groups. The primary endpoints were the overall pathological LPLNM positivity rate and different clinical characteristics between the two groups. The secondary endpoint was the identification of predictive factors of pathological LPLNM before surgery. Among the 64 patients, 24 (37.5%) had pathologically confirmed LPLNM, and pathological LPLNM was related to initial lymph node size. When initial LPLN size was <7 mm, the pathological LPLNM rate was 10.5%, whereas when LPLN size was between 7 and 10 mm, the rate was 34.6%, and when LPLN size was >10 mm, the rate was 68.4%. Initial LPLN size (≥7.1 mm, P=0.003) and cN stage (N1-2, P=0.005) were significantly associated with pathological LPLNM. In multivariate analysis of risk factors, initial LPN size (≥7.1 mm; hazard ratio=4.856, 95% confidence interval 1.158-20.359, P=0.031) was the only independent risk factor for pathological LPLNM. When the cut-off initial LPLN size was 7.1 mm, the sensitivity and specificity were 87.5 and 52.5%, respectively, and the area under the curve was 0.748 (P=0.0009). When both LPLN size ≥7.1 mm and cN1-2 were satisfied, the sensitivity was 66.7%, the specificity increased to 77.5%, and the positive and negative predictive values were 64.0 and 79.5%, respectively. In conclusion, initial LPLN size and cN stage were identified as significant clinical characteristics associated with pathological LPLNM. Patients with an initial LPLN size of ≥7.1 mm and with cN1-2 stage cancer could benefit from TME + LLND surgery.