Tumor micrometastases in mesorectal lymph nodes and their clinical significance in patients with rectal caner.
OBJECTIVE
To investigate the number, size, and status of lymph nodes within the mesorectum and to explore the prognostic significance of lymph node micrometastases in patients with rectal cancer.


METHODS
Thirty-one patients with rectal cancer undergone total mesorectal excision between October 2001 and October 2002 were included. Mesorectal nodes retrieved from the resected specimens were detected with a combination of haematoxylin and eosin (HE) staining and immunohistochemistry (IHC). The relations between lymph node metastases, micrometastases and postoperative recurrence were analyzed.


RESULTS
A total of 548 lymph nodes were harvested, with 17.7+/-8.2 nodes per case. The average number of metastatic nodes in HE-positive patients and micrometastatic nodes in IHC-positive patients was 5.2+/-5.1 per case and 2.2+/-1.3 per case, respectively. The mean size of all nodes and metastatic nodes was 4.1+/-1.8 mm and 5.2+/-1.7 mm in diameter, respectively. The mean size of micrometastatic nodes was 3.9+/-1.4 mm in diameter. The size of the majority of mesorectal nodes (66.8%), metastatic nodes (52.6%), and micrometastatic nodes (79.5%) was less than 5 mm in diameter. During a median follow-up period of 24.6+/-4.7 mo, 5 patients (16.7%) had recurrence, of them 2 died and 3 survived. Another case died of tumor unrelated cause and was excluded. All 5 recurrent cases had 3 or more nodes involved, and one of them developed only lymph node micrometastases. The mean number of both metastatic and micrometastatic nodes per case differed significantly between the recurrent and non-recurrent groups (P<0.01 and P = 0.01, respectively).


CONCLUSIONS
The majority of lymph nodes, metastatic, and micrometastatic lymph nodes within the mesorectum are smaller than 5 mm in diameter. The nodal status and the number of lymph nodes involved with tumor metastases and micrometastases are related to the rapid postoperative recurrence.
Department of Gastroenterological Surgery, West China Hospital, Sichuan University, 37 Guo Xue Xiang, Chengdu 610041, Sichuan Province, China.
Yang-Chun
YC
Zheng
Yu-Ying
YY
Tang
Zong-Guang
ZG
Zhou
Li
L
Li
Tian-Cai
TC
Wang
Yi-Ling
YL
Deng
Dai-Yun
DY
Chen
Wei-Ping
WP
Liu
D000328:Adult; D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D011379:Prognosis; D012004:Rectal Neoplasms / Q000556:secondary*