Predictors of lymph node metastasis in T1 rectal cancer
Khoshy Osman, Carl-Fredrik Rönnow, Henrik ThorlaciusAbstract
Introduction
The risk of LNM is the key determinant for recommending additional surgery following local resection of T1 rectal cancer (RC). However, the importance some of the established histopathological risk factors remains uncertain. Therefore, the primary aim of this study is to examine clinical and histopathological risk factors associated with lymph node metastasis (LNM) in T1 RC.
Methods
Retrospective population-based cohort including patients with T1 RC recorded in the Swedish Colorectal Cancer Registry who underwent surgical resection without prior neoadjuvant therapy between 2011 and 2023. Factors included were sex, age, depth of submucosal invasion depth (Sm), lymphovascular invasion (LVI), perineural invasion (PNI), histological grade, mucinous subtype, and tumour location within the rectum (distal: 0–5 cm from the anal verge, mid: 5–10 cm, proximal: 10–15 cm).
Results
Among 1010 patients, 125 (12%) had LNM. In patients without risk factors, the incidence was 6%, increasing to 10% when Sm≥2 was present as the sole factor. Additional increase was seen with accumulation of LVI and PNI to Sm>2, reaching 40 and 67%, respectively. On multivariate logistic regression, LVI (adjusted odds ration [aOR] 2.0; 95% confidence interval [CI] 3.9–9.8), PNI (aOR 6.5; 95% c.i. 2.3–18.5), Sm3 (aOR 2.0; 95% c.i. 1.1–3.9), and proximal tumour location (aOR 2.1; 95% c.i. 1.1–4.1) were associated with LNM.
Discussion
In this cohort, LNM occurred in 12% of T1 rectal cancer patients, with risk increasing in the presence of multiple pathological factors in addition to Sm≥2. LVI, PNI, Sm3, and proximal tumour location were independently associated with LNM.