Comparison of positive lymph node ratio with an inflammation-based prognostic score in colorectal cancer

Background: Two prognostic scoring systems have been proposed in colorectal cancer: the pathologically based positive lymph node ratio (pLNR) and the inflammation-based modified Glasgow Prognostic Score (mGPS). This study compared these two scores with the tumour node metastasis (TNM) staging system in terms of cancer survival. Methods: Between 2003 and 2005, 206 patients, of mean(s.d.) age 69.9(10.6) (range 40-95) years, underwent curative resection for colorectal cancer in two centres. Age, sex, primary tumour site and whether radio/chemotherapy was given were recorded in addition to the three scores (TNM stage, pLNR and mGPS). Univariable and multivariable analyses of overall survival were performed. Results: Age, rectal cancer, TNM stage, pLNR and mGPS were significant factors in univariable analysis. On multivariable analysis, N category and tumour stage (I-III) were removed from the model, leaving pLNR and mGPS as independent predictors of overall survival: hazard ratio 1.51 (95 per cent confidence interval 1.24 to 1.84; P < 0.001) and 1.56 (1.18 to 2.08; P = 0.020) respectively. C-statistic analysis, used to compare pLNR and mGPS directly, found only pLNR to be significant (P < 0.001) Conclusion: This study found pLNR to be the superior prognostic scoring system in determining long-term survival in patients undergoing resection for colorectal cancer.