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Open Access Research article

The extramural metastasis might be categorized in lymph node staging for colorectal cancer

Hai-Bo Qiu123, Gong Chen14, Rajiv P Keshari13, Hui-Yan Luo, Wang Fang15, Miao-Zhen Qiu12, Zhi-Wei Zhou13* and Rui-Hua Xu12*

Author Affiliations

1 State Key Laboratory of Oncology in South China, Guangzhou, Guangdong, 510060, P. R. China

2 Department of Medical Oncology, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, 510060, P. R. China

3 Department of Gastric & Pancreatic Surgery, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, 510060, P. R. China

4 Department of Colorectal Surgery, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, 510060, P. R. China

5 Department of Pathology, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, 510060, P. R. China

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BMC Cancer 2011, 11:414  doi:10.1186/1471-2407-11-414

Published: 26 September 2011

Abstract

Background

The objective of this study is to assess the clinical significance and prognostic impact of extramural metastasis in colorectal carcinoma and establish an optimal categorization in the staging system.

Methods

To determine the frequency and prognostic significance of extramural metastasis, from 2000 to 2005, a total of 1,215 patients with colorectal cancer who underwent surgical resection were recruited into this study. Individual demographic and clinicopathologic data were collected including tumor stage, nodal stage, tumor histology, degree of tumor differentiation, and presence of lymphovascular invasion. After surgery, all patients received standard treatments and follow-up, which were closed in April 2010.

Results

EM was detected in 167 (13.7%) patients and in 230 (1.8%) of the 12,534 nodules retrieved as 'lymph nodes'. The incidence of extramural metastasis was significantly higher in patients with large tumors, deeper invasive depth and more lymph node metastasis (P < 0.001). After curative operation, overall survival was significantly worse for patients with extramural metastasis than those without (P < 0.001). Multivariate analysis identified extramural metastasis as an independent prognostic factor (RR = 2.1, 95%CI:1.5-3.0). By using the Akaike information criterion (AIC), N staging was capable of predicting survival outcome with the highest accuracy when both nodal involvement and extramural metastasis were treated together as N factors(AIC = 1025.3).

Conclusion

Extramural metastasis might be diagnosed as replaced lymph nodes in the process of classification, thus forming a new categorization.

Keywords:
extramural metastasis; staging; colorectal cancer