To assess the efficacy and safety of salvage tratment with Gemcitabine and S-1 Combination in metastatic colorectal cancer

Inclusion Criteria:

• non resectable colorectal adenocarcinoma.
• disease progression during or within 6months after treatment with irinotecan and oxaliplatin contaning regimens.
• estimated life expectancy of more than 3 months.
• ECOG status 2 or lower

Exclusion Criteria:

• other tumor type than adenoarcinoma.
• presence or history of CNS metastasis.
• evidence of gastrointestinal bleeding.