Inclusion Criteria:

- Histologically documented adenocarcinoma of the colon or rectum.

- Advanced and/or metastatic disease, incurable with standard therapy.

- Unresectable advanced and/or metastatic unidimensionally measurable disease (RECIST
scale).

- Eastern Cooperative Oncology Group (ECOG) performance status 0, 1 or 2

- Age: over 18 years.

- Adequate haematological, renal and hepatic functions

- Patient consent must be obtained according to local REB requirements.

- Patients must be accessible for treatment and follow up.

Exclusion Criteria:

- Previous or concurrent malignancies

- Pregnant or lactating women. Women of childbearing potential must have had a negative
pregnancy test within 7 days prior to registration.

- Concurrent treatment with other experimental drugs or anticancer therapy.

- Previous chemotherapy for advanced and/or metastatic disease.

- Previous adjuvant therapy with irinotecan or oxaliplatin.

- Previous full dose curative pelvic radiation therapy.

- Patients with documented brain metastases.

- Serious illness or medical condition.

- Gilbert's disease

- Use of enzyme inducing anticonvulsants such as phenytoin, phenobarbital and
carbamazepine