[Predicting pN positivity in T3 rectal cancer]

Stage pN+ is a factor which determines the strategy for treatment of T3 rectal cancer. The sensitivity of preoperative imaging examinations revealing N+ is not entirely satisfactory. Risk factors that are associated with pT3pN+ stage and that are detectable by preoperative examination have not been reliably identified. The aim of the study is to analyze the predictive factors determining lymph node involvement in T3 rectal cancer.

Patients with rectal resection for (y)pT3 rectal cancer were analysed. All of the surgical interventions were performed at the Department of Surgery, University Hospital in Hradec Kralove, from 1 January 2011 to 28 February 2014. Data were prospectively collected and saved in the Rectal Cancer Oncologic Register. The parameters studied were age, gender, tumour localisation and its circumferential topography, preoperative chemoradiotherapy, absolute number of harvested lymph nodes and the number of positive lymph nodes in each specimen, tumour grading, presence of lymphovascular invasion and perineural invasion, and the depth of tumour penetration.

After selection, 89 patients with T3 rectal cancer were included into the study. Resection for cancer of the upper rectum was performed in 22 (24.7%) patients, middle rectum in 37 (41.6 %) and lower rectum in 30 (33.7%) patients. 38 (42.7%) patients underwent primary operation, 41 (46.1%) patients received neoadjuvant chemoradiotherapy, and radiation therapy was administered to only 10 (11.2%) patients. Stage pN+ was found in 51 (57.3%) patients. Statistical analysis was used to identify the risk factors for pN+: lymphovascular invasion (p0.001), angioinvasion (p=0.030) and perineural invasion (p=0.010). On the border of statistical significance for pN+, low grading of the tumour (p=0.084) was found. The depth of penetration of the tumour into the mesorectum was not statistically significant (p=0.230).

Our study has shown that pN positivity is associated with lymphovascular invasion, perineural invasion and low grading of the tumour. Accurate identification of these factors before treatment, however, remains very difficult.