Data of 320 patients with stage 0 - III CRC were collected for this study. With five-year overall survival as the endpoint, the optimal cut-off value for CAR was determined using the area under the curve (AUC) of the ROC curve. The preoperative cut-off value was 0.038 (AUC=0.666), the cut-off value on POD1 was 2.007 (AUC=0.649), and the cut-off value on POD7 was 0.859 (AUC=0.632).
Analysis of preoperative CAR
First, we reviewed preoperative CAR. Before propensity score matching, there were 144 patients in the high CAR group (CAR ≥ 0.038) and 176 patients in the low CAR group (CAR < 0.038). Patients in the high CAR group were older than those in the low CAR group (73.82 ± 10.79 years vs. 68.62 ± 11.83 years; p <0.001) and had a higher proportion of males (59.7% vs. 46.0%; p=0.018). In addition, the high CAR group (vs. low CAR group) showed significant differences in ASA-PS (p <0.001), preoperative CEA (CEA ≥5: 48.6% vs. 30.1%; p=0.001), tumor size (≥50mm: 47.2% vs. 15.3%; p <0.001), lymphatic invasion (54.9% vs. 40.9%; p=0.014), venous invasion (51.4% vs. 33.0%; p=0.001), and pathological stage (p <0.001). The two groups were then propensity score-matched in a 1:1 ratio (n=93/group), and there were no differences between groups (Table 1). There was no significant difference in postoperative complications either before or after propensity score matching.
Before propensity score matching, the five-year RFS was 66.4% in the high CAR group compared to 82.7% in the low CAR group (p <0.001). Also, five-year OS was 74.5% in the high CAR group and 89.5% in the low CAR group (p <0.001) (Figure. 1A and B). After propensity score matching, the results showed that five-year RFS was 73.3% in the high CAR group and 76.1% in the low CAR group (p=0.784). The 5-year OS was 83.0% in the High CAR group and 85.7% in the Low CAR group (p=0.669) (Figure. 1C and D).
Analysis of CAR on POD1
Second, we reviewed CAR of POD1. Before propensity score matching, there were 95 patients in the high CAR group (CAR ≥ 2.007) and 225 patients in the low CAR group (CAR < 2.007). The high CAR group (vs. low CAR group) showed significant differences in age (74.03 ± 11.19 vs. 69.67 ± 11.61; p=0.002), ASA-PS (p <0.001), preoperative CEA (CEA ≥5: 51.6% vs. 32.9%; p=0.002), tumor size (≥50 mm: 43.2% vs. 24.0%; p=0.001), lymphatic invasion (60.0% vs. 41.8%; p=0.003), venous invasion (52.6% vs. 36.4%; p=0.009), and pathologic stage (p=0.026). Next, the two groups were propensity score matched in a 1:1 ratio (n=81/group), but no differences were observed between groups (Table 2). For postoperative complications, there was a significant difference even after propensity score matching.
Before propensity score matching, the five-year RFS was 62.7% in the high CAR group and 80.5% in the low CAR group (p <0.001). Five-year OS was 68.4% in the high CAR group and 88.5% in the low CAR group (p <0.001) (Figure. 2A and B). After propensity score matching, five-year RFS was 66.6% in the high CAR group and 71.5% in the low CAR group (p=0.220). Five-year OS was 70.1% in the high CAR group and 83.4% in the low CAR group (p=0.059) (Figure. 2C and D).
Analysis of CAR on POD7
Finally, we reviewed the CAR of POD7. Before propensity score matching, there were 75 patients in the high CAR group (CAR ≥ 0.859) and 245 patients in the low CAR group (CAR < 0.859). The high CAR group (vs. low CAR group) was older (74.32±9.64 vs. 69.94±12.02; p=0.004), consisted of a higher proportion of males (69.3% vs. 46.9%; p=0.001), and showed significant difference in ASA-PS (p <0.001). The two groups were then propensity score matched at a ratio of 1:1, and the number of patients in both groups was 72 each, with no significant differences in any of the measured variables (Table 3). There was a significant difference in postoperative complications even after propensity score matching.
Before propensity score matching, the five-year RFS was 50.0% in the high CAR group and 82.6% in the low CAR group (p <0.001). Five-year OS was 63.8% in the high CAR group and 88.1% in the low CAR group (p <0.001) (Figure. 3A and B). After propensity score matching, five-year RFS was 49.6% in the High CAR group and 79.6% in the low CAR group (p <0.001). Five-year OS was 64.0% in the high CAR group and 84.6% in the Low CAR group (p=0.002) (Figure. 3C and D).
Out of the 144 patients selected by propensity score matching from POD7 results, an additional comparison was made between patients with postoperative complications (19 patients) and patients without postoperative complications (125 patients). The five-year RFS was 65.2% for patients with postoperative complications and 65.0% for patients without postoperative complications (p=0.989). Five-year OS was 72.4% in patients with postoperative complications and 75.0% in patients without postoperative complications (p=0.964) (Figure. 4A and B). The results showed that the presence of postoperative complications did not affect survival rate.
As shown above, before propensity score matching, all CARs of preoperative, POD1, and POD7 were associated with prognosis. However, after propensity score matching and background equalization, only the CAR of POD7 was found to have a significant relationship with the prognosis of CRC patients.