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. 2021 Jan-Dec:28:10732748211064034.
doi: 10.1177/10732748211064034.

Examining More Lymph Nodes May Improve the Prognosis of Patients With Right Colon Cancer: Determining the Optimal Minimum Lymph Node Count

Wentao Wu  1   2 , Daning Li  2 , Wen Ma  1   2 , Shuai Zheng  1 , Didi Han  1   2 , Fengshuo Xu  1   2 , Hong Yan  2 , Jun Lyu  1   2
Affiliations

Examining More Lymph Nodes May Improve the Prognosis of Patients With Right Colon Cancer: Determining the Optimal Minimum Lymph Node Count

Wentao Wu et al. Cancer Control. 2021 Jan-Dec.

Abstract

Objectives: The objective is to determine the optimal minimum lymph node examination number for right colon cancer (RCC) patients.

Methods: We comprehensively analysed the Surveillance, Epidemiology and End Results database data from 2004 to 2016 to determine the 13-year trend in the number of lymph nodes examined among 108,703 left colon cancer and 165,937 RCC patients. 133,137 RCC patients eligible for inclusion were used to determine the optimal minimum for lymph node examination. We used restricted cubic splines to analyse the dose-response relationship between the number of lymph nodes examined and prognosis. X-tiles and decision trees were used to determine the optimal cutoff for the number of lymph nodes based on the survival outcomes of patients with RCC. The Kaplan-Meier method and COX model were used to estimate the overall survival and independent prognostic factors, and a prediction model was constructed. The C-index, calibration curve, net reclassification improvement and integrated discrimination improvement were used to determine the predictive performance of the model, and decision curve analysis was used to evaluate the benefits.

Results: Lymph node examinations were common among colon cancer patients over the 13-year study period. It is generally agreed that at least 12 lymph nodes must be examined to ensure proper dissection and accurate staging of RCC; however, the optimal number of lymph nodes to be examined is controversial. The dose-response relationship indicated that 12 was not the optimal minimum number of lymph nodes for RCC patients. X-tile and survival decision-tree analysis indicated that 20 nodes was the optimal number. Survival analysis indicated that <20 nodes examined was a risk factor for poor prognosis, and the classification performance was superior for 20 nodes compared to 12 nodes.

Conclusion: Lymph node examination in RCC patients should be altered. Our research suggests that a 20-node measure may be more suitable for RCC patients.

Keywords: dose-response relationship; lymph node examination; optimal minimum node; prognosis nomogram; right colon cancer.

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Conflict of interest statement

Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Figures

Figure 1.
Figure 1.
Flow chart for patient selection.
Figure 2.
Figure 2.
Percentage of patients with lymph node excision (≥1, ≥12, ≥20 nodes) by year. (A) Percentage of colorectal cancer (CRC) patients with lymph node excision (≥1, ≥12 and ≥20 nodes) by year. (B) Percentage of left colon cancer (LCC) patients with lymph node excision (≥1, ≥12 and ≥20 nodes) by year. (C) Percentage of right colon cancer (RCC) patients with lymph node excision (≥1, ≥12 and ≥20 nodes) by year.
Figure 3.
Figure 3.
Mean number of lymph nodes excised by year of diagnosis in all patients and those who underwent a lymph node excision. (A) Mean number of lymph nodes excised by year of diagnosis in CRC patients and those who underwent a lymph node excision. (B) Mean number of lymph nodes excised by year of diagnosis in LCC patients and those who underwent a lymph node excision. (C) Mean number of lymph nodes excised by year of diagnosis in RCC patients and those who underwent a lymph node excision.
Figure 4.
Figure 4.
Dose-response relationship between number of lymph node examined and risk of death.
Figure 5.
Figure 5.
Identification of the optimal cut-off point of lymph node count for RCC patients. (A) Result based on the x-tile software. (B) Result of the decision-tree algorithm.
Figure 6.
Figure 6.
Prognostic impact of the 20-node measure on overall survival (OS) for RCC patients with different AJCC stage. (A) Survival curve of patients with all AJCC stage. (B) Survival curve of patients with AJCC stage I. (C) Survival curve of patients with AJCC stage II. (D) Survival curve of patients with AJCC stage III. (E) Survival curve of patients with AJCC stage IV.
Figure 7.
Figure 7.
Mean number of positive nodes in different groups.
Figure 8.
Figure 8.
Nomogram predicting 3-, 5- and 8-year survival.
Figure 9.
Figure 9.
Calibration curves for the nomogram. (A) Calibration curves for 3-year survival of the training cohort. (B) Calibration curves for 3-year survival of the validation cohort. (C) Calibration curves for 5-year survival of the training cohort. (D) Calibration curves for 5-year survival of the validation cohort. (E) Calibration curves for 8-year survival of the training cohort. (F) Calibration curves for 8-year survival of the validation cohort.
Figure 10.
Figure 10.
DCA curves for the nomogram. (A) DCA curve for 3-year survival of the training cohort. (B) DCA curve for 3-year survival of the validation cohort. (C) DCA curve for 5-year survival of the training cohort. (D) DCA curve for 5-year survival of the validation cohort. (E) DCA curve for 8-year survival of the training cohort. (F) DCA curve for 8-year survival of the validation cohort.
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