To assess the efficacy and safety of gemcitabine given by fixed dose rate intravenous infusion in patients with pretreated metastatic colorectal cancer.

Previous lines of treatment recorded. Adjuvant and palliative.

Treatment will continue until clinical indication due to PD or toxicity, or until completion of 6 cycles of gemcitabine, whichever comes first.

All patients will be assessed for toxicity and followed up for disease recurrence/progression.

The study will be divided into two accrual stages - the first consisting of 17 patients. If 6 or more patients achieve tumour response or stabilisation in the first stage, the second stage will commence accrual of a further 20 patients. Hence, the total planned accrual will be 37 patients.

Inclusion Criteria:

• Age >18 years
• Histologically proven colorectal adenocarcinoma.
• Locally advanced (inoperable) or metastatic colorectal carcinoma treated with at least one prior chemotherapy regimen.
• Progressive disease documented by CT either during or within 3 months of completion of previous chemotherapy
• No previous malignant disease other than non-melanotic skin cancer or carcinoma-in-situ of the uterine cervix.
• Unidimensional measurable disease as assessed by CT.
• Adequate bone marrow function; Hb >10g/dl, platelets >100 x109/l, WBC >3x109/l, Neut >1.5x109/l.
• Adequate liver function: Serum Bilirubin <1.5 x upper limit of normal
• Adequate renal function: Serum Creatinine < 0.11 mmol/L
• No concurrent uncontrolled medical conditions
• WHO performance status 0,1 or 2
• Adequate contraceptive precautions, if appropriate
• Informed written consent
• Negative pregnancy test in women of child bearing age
• Life expectancy > 3 months

Exclusion Criteria:

• Medical or psychiatric condition that comprise the patient's ability to take informed consent.
• Patients within 4 weeks of chemotherapy or radiotherapy (6 weeks for nitrosureas or mitomycin C).
• Previous treatment with gemcitabine.
• Patients with uncontrolled cerebral metastases.