Colorectal adenocarcinoma:

Abstract

We have studied 193 cases of colorectal adenocarcinoma from a population-based register to determine the minimum number of lymph nodes to be examined to provide an accurate assessment of the presence of nodal metastases. The mean total number of lymph nodes identified per surgical specimen was 11 +/- 6.8 (range, 1-36) using traditional dissection. One hundred eighteen specimens (61 percent) were classified as Dukes B. Seventy-five (39 percent) had lymph node metastases (Dukes C) with a mean of 3.3 +/- 4.7 positive lymph nodes per specimen. With binomial distribution we calculate the probability to find at least one positive node in a sample size n with a determined proportion of positive nodes. The error probability in the ganglionar assessment by traditional dissection was 0.05 with 6 examined lymph nodes and 0.01 with 10 examined nodes. We must provide the pathologist with a minimum of six examined lymph nodes per surgical specimen for an optimal Dukes B assessment.