Investigation of Association Between UGT1A1 Polymorphisms and Irinotecan Toxicity in Korean Patients

Inclusion Criteria:Subjects should meet all of the following criteria to participate in the trial. * Histologically confirmed colorectal or gastric cancer patients who are chemonaive or failed to 1st line chemotherapy * Subjects who are expected to receive toxicity test at least once after FOLFIRI treatment. * Aged 18 years or older. * ECOG performance status of ≤ 2. * Anticipated life expectancy of ≥ 3 months. * Clinically acceptable function of bone marrow, kidney and liver function as below. 1. ANC ≥ 1500/mm3 and platelet count ≥ 100,000/mm3 2. Serum total bilirubin ≤ 1.5 x ULN, alkaline phosphatase ≤ 2.5 x ULN, Serum ALT and AST ≤ 2.5 x ULN (Serum ALT and AST ≤ 5 x ULN, if liver metastases are present) 3. Serum creatinine ≤ 1.5 mg/dL or CLcr \> 60 ml/min * Subjects whose written informed consent can be obtained prior to their participation in the trial. Exclusion Criteria: Subjects who meet any of the following criteria should not be included in the trial. * Pregnant or breast feeding women * Serious concurrent complication, severe active infection. * Subjects with chronic diarrhea, paralytic ileums, pulmonary fibrosis or pneumonia interstitialis * Subjects with epilepsia or severe psychiatric disorders. * Subjects who are regarded to be unsuitable for this trial by the investigator. * Subjects who are participating in other clinical trials * Subjects who have received prior chemotherapy including irinotecan.