Abstract
Lymph node stages (pN stages) are primary contributors to survival heterogeneity of the 7th AJCC staging system for colorectal cancer (CRC), indicating spaces for modifications. To implement the modifications, we selected eligible CRC patients from the Surveillance Epidemiology and End Results (SEER) database as participants in a training (n = 6675) and a test cohort (n = 6760), and verified tumor deposits to be metastatic lymph nodes to derive modified lymph node count (mLNC), lymph node ratio (mLNR), and positive lymph node count (mPLNC). After multivariate Cox regression analyses with forward stepwise elimination of the mLNC and mPLNC for the training cohort, a nomogram was constructed to predict overall survival (OS) via incorporating preoperative carcinoembryonic antigen, pT stages, negative lymph node count, mLNR and metastasis. Internal validations of the nomogram showed concordance indexes (c-index) of 0.750 (95% CI, 0.736–0.764) and 0.749 before and after corrections for overfitting. Serial performance evaluations indicated that the nomogram outperformed the AJCC stages (c-index = 0.725) with increased accuracy, net benefits, risk assessment ability, but comparable complexity and clinical validity. All the results were reproducible in the test cohort. In summary, the proposed nomogram may serve as an alternative to the AJCC stages. However, validations with longer follow-up periods are required.
Highlights
Colorectal cancer (CRC) is the third leading cause of cancer morbidity and mortality worldwide[1]
We anticipated that the expression of carcinoembryonic antigen (CEA), the presence of tumor deposits (TDs) and node-related parameters including the lymph node count (LNC), NLNC, positive lymph node count (PLNC) and LNR could explain and address to a certain degree the survival heterogeneity caused by the pN stages
We evaluated the survival heterogeneity that results from use of the pN stages and proposed a new prognostic nomogram that was able to avoid the limitations associated with the American Joint Committee on Cancer (AJCC) staging system
Summary
Colorectal cancer (CRC) is the third leading cause of cancer morbidity and mortality worldwide[1]. We anticipated that the expression of CEA, the presence of TDs and node-related parameters including the LNC, NLNC, PLNC and LNR could explain and address to a certain degree the survival heterogeneity caused by the pN stages. Modifications of the pN stages by the addition of CEA expression, TDs and node-related factors to a multivariate nomogram might improve its predictive accuracy for CRC. To test this hypothesis, we retrospectively reviewed relevant clinical-pathological variables and the vital status of CRC patients from the Surveillance Epidemiology and End Results (SEER) database. This study may help us understand the survival heterogeneity complicated by the pN stages and may offer patients with CRC an improved prognostic tool without increased complexity
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