Background: We evaluated the efficiency of CEA and CA19-9 as tools for diagnosing recurrence in the postoperative surveillance of colorectal cancer.
Materials and methods: A total of 227 patients who underwent curative resection for colorectal cancer between 1999 and 2003 at our hospital received complete follow-up according to the schedule determined prospectively. Using receiver operating characteristic (ROC) analysis, performance of postoperative values of CEA or CA19-9 for detecting recurrence was assessed.
Results: The sensitivity (1.000) and specificity (0.978) of the postoperative values of CEA in the high preoperative CEA group were very high. Even in the normal preoperative CEA group, the area under the curve (AUC) of the ROC curve of CEA (0.740, 95% confidence interval [95% CI], 0.628-0.852) was significantly larger than 0.5 (P < 0.001). The postoperative values of CA19-9 showed high sensitivity (0.833) and specificity (0.900) in the high preoperative CA19-9 group, while the AUC of the ROC curve of the normal preoperative group was as small as 0.510 (95% CI, 0.376-0.644). In the high preoperative CA19-9 group, however, there was no significant difference between the AUC of CA19-9 (0.904, 95% CI, 0.786-1.000) and that of CEA (0.869, 95% CI, 0.744-0.994) (P = 0.334).
Conclusions: The measurement of CEA is an efficient way to detect recurrence. The efficiency of measuring CA19-9 for the purpose of detecting recurrence is low, especially in patients with a normal level of preoperative CA19-9. Even in patients with a high preoperative level of CA19-9, CEA might be able to fill the role of CA19-9.