Pretreatment selection of regimen according to genetic analysis improves the efficacy of chemotherapy in the first line treatment of metastatic colorectal cancer.

Abstract

BACKGROUND AND OBJECTIVES: Metastatic colon cancer patients are treated with the

chemotherapy regimens, FOLFOX and FOLFIRI, in either order. So far, we cannot

predict the response of chemotherapeutic agent, so it is necessary to find which

regimen is adequate before starting chemotherapy. METHODS: Enrolled patients are

randomized into either conventional treatment or planned treatment preceded by

pretreatment genetic analysis. Blood samples of patients in planned treatment

group (N = 53) were analyzed for the genetic polymorphism before selection of

chemotherapeutic agents. Target genes were XPD-751, GSTP-1-105, XRCC1-399 for

oxaliplatin, UGT1A1 for irinotecan. The response was measured by computed

tomographic scan after completion of three cycles of chemotherapy. RESULTS:

Overall response rate was significantly higher in planned group (67.9% vs. 46.3%,

P = 0.020). In FOLFOX group, response rate was significantly improved in the

planned patients(77.1% vs. 50%, P = 0.018). In FOLFIRI group, the difference

didn't reach statistical significance (50% vs. 42.5%, P = 0.776). CONCLUSIONS: We

found significantly improved response rates in the chemotherapy of metastatic

colon cancer by pretreatment genetic analysis, especially in FOLFOX group.