Gemcitabine is a commercially available drug for the treatment of patients with locally advanced or metastatic adenocarcinoma of the pancreas. In the GEM arm, gemcitabine will be administered by intravenous infusion over 30 minutes at a dose of 1000 mg/m2. The dosing schedule of gemcitabine will be once weekly for the first cycle (4 weeks), then once weekly for 3 consecutive weeks followed by a week of rest for each subsequent cycle. Gemcitabine therapy will be continued until unacceptable toxicity, documented progression of disease, or another discontinuation criterion is met.