Study of DPD for Predicting Efficacy and Safety to S-1 Plus Oxaliplatin in Gastrointestinal Cancer

Inclusion Criteria:

* Age ≧18;
* Histologically or cytologically confirmed gastrointestinal cancer；
* ECOG ≦2;
* Physician's intention to treat with S-1 combined with platinum regimen on disease status and clinical judgment;
* Life expectancy of at least three months;
* Written informed consent to participate in the trial;

Exclusion Criteria:

* History of severe hypersensitivity reactions to the ingredients of S-1 or oxaliplatin;
* Inadequate hematopoietic function which is defined as below:

  * white blood cell (WBC) less than 3,500/mm\^3
  * absolute neutrophil count (ANC) less than 1,500/mm\^3
  * platelets less than 80,000/mm\^3
* Inadequate hepatic or renal function which is defined as below:

  * serum bilirubin greater than 1.5 times the upper limit of normal range
  * alanine aminotransferase (ALT) or aspartate aminotransferase (AST)
  * greater than 2.5 times the ULN if no demonstrable liver metastases or
  * greater than 5 times the ULN in the presence of liver metastases
  * blood creatinine level greater than 2 times ULN
* Presence of peripheral neuropathy;
* Receiving a concomitant treatment with other fluoropyrimidine drug or flucytosine drug;
* Women who is pregnant or lactating or fertile women of child-bearing potential unless using a reliable and appropriate contraceptive method throughout the treatment period (Including male);
* Psychiatric disorder or symptom that makes participation of the patient difficult;
* Concomitant illness that might be aggregated by active, non-controlled disease such as congestive heart failure, ischemic heart disease, uncontrolled hypertension or arrhythmia with in six months;
* Severe complication(s), e.g., paresis of intestines, ileus, radiographically confirmed interstitial pneumonitis or pulmonary fibrosis, glomerulonephritis ,renal failure, poorly-controlled diabetes;
* Known DPD deficiency;
* Receiving a concomitant treatment with sorivudine or Brivudine within two months;