[Predictive value of combination detection of tissue Pgp1 expression and preoperative serum CEA level for colorectal cancer].

OBJECTIVE: To explore the predictive value of combination detection of Pgp1 expression in cancer tissue and serum CEA level for the prognosis of colorectal cancer (CRC) patients.

METHODS: Clinicopathological data, complete 5-year follow-up data and CRC tissue samples of 153 CRC patients with stage I( to II( tumor undergoing radical operation in our department from January 2004 to August 2006 were retrospectively collected. Immunohistochemical staining was used to detect the expression level of Pgp1. The combined evaluation of staining intensity and positive cell percentage was performed to determine the expression level of Pgp1. Pgp1 staining (-) and (+) was defined as low expression; and staining (++) and (+++) as high expression. Electrochemiluminescence immunoassay was used to detect the level of serum CEA. CEA > 5 μg/L was defined as positive. χ(2) and Fisher's exact test were performed to analyze the association of Pgp1 expression with CEA level and clinicopathological variables. Moreover, Kaplan-Meier method was used to analyze the survival. Univariate and multivariate Cox proportional hazard regression models were used to evaluate the roles of Pgp1 expression combined with serum CEA level in prognosis prediction.

RESULTS: Of 153 patients, 105 were males and 48 females with mean age of 59 (27 to 90) years; 41 cases were rectal cancer, and 112 cases colon cancer; 23 patients were TNM stage I( tumor, and 130 patients stage II( tumor; median follow-up time was 64 months; 30 cases were dead. Positive rate of Pgp1 expression in colorectal cancer tissues was 66.0%(101/153). The expression of Pgp1 was associated with gender, tumor location, and survival during the follow-up (all P<0.05). The preoperative positive rate of serum CEA was 28.1% (43/153). The preoperative serum CEA level was associated with tumor recurrence and survival (all P<0.05). Kaplan-Meier analysis showed the overall 5-year survival rate was 81.7%. The 5-year survival rate of patients with high expression of Pgp1 was 88.1%, which was significantly higher than 69.2% of those with low expression of Pgp1(P=0.003). The 5-year survival rate of patients with preoperative positive serum CEA was 72.1%, which was significantly lower than 86.1% of those with preoperative negative serum CEA(P=0.023). Furthermore, the 5-year survival rate of patients with negative Pgp1 plus positive CEA was 66.7%, which was significantly lower than 91.0% of those with positive Pgp1 plus negative CEA(P=0.002). Univariate analysis showed that gender, Pgp1 expression level, preoperative serum CEA level, and Pgp1 combined with CEA were significantly associated with the prognosis of patients(all P<0.05). Multivariate analysis showed that Pgp1 expression was an independent prognostic factor of CRC [HR(95%CI:1.261 to 64.224), P=0.028].

CONCLUSIONS: Low expression of Pgp1 in cancer tissue indicates poor prognosis in patients with stage I( and II( tumor. Combination detection of Pgp1 expression and serum CEA can be applied to predict the prognosis of patients with stage I( and II( colorectal cancer.