Background: The presence and number of nodal metastasis significantly impact colon cancer prognosis. Similarly, the number of resected/evaluated nodes impacts staging accuracy. This ratio of metastatic to examined nodes or lymph node ratio (LNR) may have independent prognostic value in colon carcinoma.
Purpose: To evaluate the impact of LNR on overall survival in colon cancer patients with fewer than 12 or 12 examined nodes or more.
Methods: Patients (n = 36,712) with node-positive nonmetastatic colon cancer diagnosed between 1992 and 2004 were identified from the Surveillance, Epidemiology, and End Results database and stratified according to LNR and number of nodes examined. Survival was estimated by Kaplan-Meier method, and differences analyzed by log-rank test. A Cox proportional hazards model was used for multivariate analysis.
Results: Patients with fewer than 12 nodes were older and male and had lower primary tumor stage, grade, and N stage (P < 0.01). Survival appeared greater with 12 total nodes examined or more (median 53 vs. 66 months, P < 0.001). Within each LNR stratum, survival with 12 nodes or more was improved for those with less than 10% of nodes positive for cancer, but was worse with higher LNRs (P < 0.01). Lymph node ratio was significantly associated with survival independent of total nodes (HR 1.24–5.12, P < 0.001). Other significant factors included age, race, tumor grade, stage, location, and N stage.
Conclusion: Metastatic LNR independently estimates survival in Stage III colon cancer, irrespective of number of nodes examined. However, statistically significant differences in each LNR stratum between those with resection of fewer than 12 or 12 nodes or more would indicate that a 12-node minimum may still be necessary for accurate staging.
We studied the impact of lymph node ratio (LNR) on overall survival in colon cancer patients with fewer than 12 or 12 or more examined nodes. Metastatic LNR independently estimates survival in stage III colon cancer, irrespective of number of nodes examined. However, statistically significant differences in each LNR stratum between those with resection of fewer than 12 or 12 or more nodes would indicate that a 12-node minimum may still be necessary for accurate staging.
*Department of Surgery, University of California, Davis, CA
†Department of Surgery, Madigan Army Medical Center, Tacoma, WA
‡DecisionQ Corporation, Washington, DC
§Clinical Trials Group, United States Military Cancer Institute, Washington, DC
¶Department of Medicine, Los Angeles and California Oncology Research Institute, University of California, Los Angeles
∥Department of Surgery, Division of Surgical Oncology, Walter Reed Army Medical Center, Washington, DC
**Department of Surgery, Uniformed Services University of the Health Sciences, Bethesda, MD.
Reprints: Alexander Stojadinovic, MD, United States Military Cancer Institute, Walter Reed Army Medical Center, 6900 Georgia Avenue, Room 5C27, N.W., Washington, DC 20307. E-mail: email@example.com.
Supported, in part, by the United States Military Cancer Institute.
Copyright Protection: Our team is composed partly of military service members and employees of the US Government. This work was prepared as part of our official duties. Title 17 U.S.C. 105 provides that “Copyright protection under this title is not available for any work of the United States Government.” Title 17 U.S.C. 101 defines a US Government work as a work prepared by a military service member or employee of the US Government as part of that person's official duties.
The views expressed in this article are those of the authors and do not reflect the official policy of the Department of the Army, the Department of Defense, or the US Government.
A.B. and A.S. were responsible for the conception and design of the work. S.L.C. contributed in the process of acquisition of data. S.L.C., J.E., K.Z., and A.S. analyzed and interpreted the data. S.L.C., S.R.S., and A.S. drafted the manuscript, which was critically revised by J.E., S.R.S, and A.B. S.L.C., J.E., K.Z., and A.S. contributed to the work by their statistical expertise. A.B. and A.S. were responsible for obtaining funds. A.B. and A.S. also supervised the work.
The authors declare no conflicts of interest.