The impact of chemotherapy-associated neutrophil/lymphocyte counts on prognosis of adjuvant chemotherapy in colorectal cancer

Background: Leukocytes play an important role in cancer development. However, the impact of chemotherapy-associated neutropenia/lymphopenia on the prognosis of adjuvant chemotherapy is unknown. Here, we aimed to explore the impact of chemotherapy-associated neutrophil/lymphocyte counts on prognosis of adjuvant chemotherapy in colorectal cancer (CRC) and the risk factors for developing neutropenia/lymphopenia which showed impact on the prognosis of CRC receiving adjuvant chemotherapy. Methods: From February 2003 to January 2011, 243 stage II and III CRC patients receiving adjuvant chemotherapy were enrolled in this retrospective study. The associations between neutrophil/lymphocyte counts and disease free survival (DFS)/overall survival (OS) of CRC, and the risk factors for neutropenia/lymphopenia were investigated. Results: No association of chemotherapy-associated neutrophil counts and CRC recurrence (AUC = 0.474, P = 0.534), death (AUC = 0.449, P = 0.249) was found by ROC analysis. However, the chemotherapy-associated lymphocyte counts could significantly affect CRC recurrence (AUC = 0.634, P = 0.001), or death(AUC = 0.607, P = 0.015), with a optimized cut-off of 0.66 x 10(9)/L for recurrence, and 0.91 x 10(9)/L for death, respectively. Kaplan-Meier method showed chemotherapy-associated lymphopenia <0.66 x 10(9)/L was associated with shorter DFS (P < 0.0001), and chemotherapy-associated lymphopenia <0.91 x 10(9)/L was associated with shorter OS (P = 0.003). Cox regression model showed chemotherapy-associated lymphopenia <0.66 x 10(9)/L was the independent prognostic factor for DFS (HR, 3.521; 95% CI = 1.703-7.282), and chemotherapy-associated lymphopenia <0.91 x 10(9)/L was the independent prognostic factor for OS (HR, 2.083; 95% CI = 1.103-3.936). Multivariate logistic regression showed the risk of developing chemotherapy-associated lymphopenia <0.66 x 10(9)/L was found in those with pretreatment CEA = 10 ng ml(-1) (OR, 3.338; 95% CI = 1.523-7.315), and the risk of developing chemotherapy-associated lymphopenia <0.91 x 10(9)/L was found in those with age >60 years (OR, 2.872; 95% CI = 1.344-6.136). Conclusions: Chemotherapy-associated lymphopenia <0.66 x 10(9)/L /0.91 x 10(9)/L has a significant impact on the prognosis of CRC receiving adjuvant chemotherapy. Pretreatment CEA = 10 ng ml(-1) is the independent risk factor for developing lymphopenia <0.66 x 10(9)/L, and age >60 years is the independent risk factor for developing lymphopenia <0.91 x 10(9)/L during adjuvant chemotherapy of CRC.