Adenocarcinoma of the lower third of the rectum: Metastases in lymph nodessmaller than 5 mm and occult micrometastases; Preliminary results on earlytumor recurrence

Background: The number of examined lymph nodes and metastases in lymph node s smaller than 5 mm (small lymph nodes) are a determining factor in the sta ge of rectal cancer although the clinical significance of occult micrometas tases is controversial. We are reporting our preliminary results on the ide ntification and prognostic utility of metastases in small lymph nodes and o ccult micrometastases. Methods: We searched small metastatic lymph nodes in 101 cases of adenocarc inoma of the lower third of the rectum. We used the manual technique to dis sect mesorectal fat and occult micrometastases in the lymph nodes of 52 Duk es' A and B patients, using a pool of anticytokeratin antibodies. Results: Forty-five percent of the metastatic lymph nodes were smaller than 5 mm in diameter and determined the Dukes' stage in 15 (30.6%) of 49 Dukes ' C patients. Occult micrometastases were found in 21 (40.4%) patients: fiv e recurred but Vascular invasion, positive distal margin of the rectum, and positive circumferential margin of the mesorectum were present. Conclusions: Small metastatic lymph nodes, vascular invasion, positive dist al margin of the rectum, and positive circumferential margin of the mesorec tum were found to be more important than occult micrometastases in predicti ng early recurrence of rectal cancer.