Irregular delay of adjuvant chemotherapy correlated with poor outcome in stage II-III colorectal cancer

Aims Adjuvant chemotherapy (ACT) plays an important role in improving the survival of stage II-III colorectal cancer (CRC) patients after curative surgery. However, the prognostic role of irregular delay of ACT (IDacT) for these patients has been less studied. Materials and methods A total of 117 stage II-III CRC patients who underwent radical resection and received at least 3 months ACT were enrolled retrospectively. The significance of IDacT, including total delay (TD) and delay per cycle (DpC), in predicting disease-free survival (DFS) was determined using receiver operating characteristic curve (ROC) analysis. The survival differences between the TD, DpC-short and DpC-long subgroups were tested using Kaplan-Meier analysis, and risk factors for prognosis were determined using a Cox proportional hazards model. Results Using 35.50 and 3.27 days as the optimal cut-off points for TD and DpC, respectively, ROC analysis revealed that TD and DpC had sensitivities of 43.60% and 59.00% and specificities of 83.30% and 62.80%, respectively, in predicting DFS (both P < 0.05). No differences in the clinicopathological parameters were found between the TD, DpC-short or -long subgroups except histological differentiation in different TD subgroups and combined T stages in different DpC subgroups (both P = 0.04). Patients in the TD or DpC-long group exhibited significantly worse survival than in the -short group (TD: Log rank = 9.11, P < 0.01; DpC: Log rank = 6.09, P = 0.01). DpC was an independent risk factor for prognosis (HR = 2.54, 95% CI: 1.32-4.88, P = 0.01). Conclusions IDacT had a profound effect on the outcome for stage II-III CRC. Although TD and DpC were significant for the prognosis, DpC was more robust, and patients who presented DpC for a long time had a significantly worse DFS.