Number of lymph nodes dissected in colorectal cancer and probability of positive nodes, angiolymphatic/perineural invasion, and intracellular mucin in a referral service

Abstract

Among the malignancies, colorectal cancer ranks fourth in incidence in Brazil. The main prognostic measure is related to the amount of affected lymph nodes. Thus, many studies try to correlate the number of extracted lymph nodes, with the probability of obtaining positive nodes. Study objectives Determine whether dissection ≥12 lymph nodes increases probability of finding neoplastic involvement in relation to resection of fewer. Assess the presence of angiolymphatic invasion; perineural and intracelluar mucin and correlate it with tumor differentiation and TNM classification. Correlate the average of positive nodes with angiolymphatic and perineural involvement. Methods Pathological reports of patients operated for CRC from 1997 to 2013 were analyzed. A probability (p) less than 0.05 was considered to indicate statistical significance. Results Median of lymph nodes sent to analysis was 12 nodes. Average number of lymph nodes affected was higher when a number ≥12 lymph nodes were dissected (p = 0.001) (Kruskal–Wallis). There was positive association between average of affected lymph nodes and presence of angiolymphatic (p < 0.0001) or perineural invasion (p = 0.024). Angiolymphatic and intracellular mucin are less present in well-differentiated adenocarcinomas. Perineural and angiolymphatic were more present in T4 stages. Conclusions Dissection ≥12 lymph nodes increases chances of finding positive nodes. There is relation between angiolymphatic invasion; perineural and intracellular mucin and type of tumor differentiation, as well as TNM classification. Average number of lymph nodes affected was higher in presence of perineural or angiolymphatic invasion.