Aim: To identify the predictors of distant metastasis in pathologically T1 (pT1) colorectal cancer (CRC) after radical resection.
Methods: Variables including age, gender, preoperative carcinoembryonic antibody (CEA) level, tumor location, tumor size, lymph node status, and histological grade were recorded. Patients with and without metastasis were compared with regard to age, gender, CEA level and pathologic tumor characteristics using the independent t test or χ(2) test, as appropriate. Risk factors were determined by logistic regression analysis.
Results: Metastasis occurred in 6 (3.8%) of the 159 patients during a median follow-up of 67.0 (46.5%) mo. The rates of distant metastasis in patients with pT1 cancer of the colon and rectum were 6.7% and 2.9%, respectively (P < 0.001). The rates of distant metastasis between male and female patients with T1 CRC were 6.25% and 1.27%, respectively (P < 0.001). The most frequent site of distant metastasis was the liver. Age (P = 0.522), gender (P = 0.980), tumor location (P = 0.330), tumor size (P = 0.786), histological grade (P = 0.509), and high serum CEA level (P = 0.262) were not prognostic factors for lymph node metastasis. Univariate analysis revealed that age (P = 0.231), gender (P = 0.137), tumor location (P = 0.386), and tumor size (P = 0.514) were not risk factors for distant metastasis after radical resection for T1 colorectal cancer. Postoperative metastasis was only significantly correlated with high preoperative serum CEA level (P = 0.001). Using multivariate logistic regression analysis, high preoperative serum CEA level (P = 0.004; odds ratio 15.341; 95%CI 2.371-99.275) was an independent predictor for postoperative distant metastasis.
Conclusion: The preoperative increased serum CEA level is a predictive risk factor for distant metastasis in CRC patients after radical resection. Adjuvant chemotherapy may be necessary in such patients, even if they have pT1 colorectal cancer.
Keywords: Carcinoembryonic antigen; Colorectal cancer; Metastasis; Pathologically T1; Risk factor.