Time to Progression (TTP) at Primary Completion: FOLFIRI and mIFL every 6 weeks until disease progression [clinicaltrials_resource:4f4310473fc7df2b4944863dececd5b0]

Day 1 & 8: Irinotecan (125 mg/m2 IV over 90 minutes), LV (20 mg/m2 IV bolus), 5-FU (500 mg/m2 IV bolus). All chemotherapy cycles repeated every 3 weeks. Celecoxib/placebo treatment will commence on the same day as chemotherapy treatment (i.e. Day 1 of treatment on study). Celecoxib/placebo will be taken at a dose of 400 mg po BID [two times a day] (800 mg/day) and will continue daily without interruption (no rest period for celecoxib/placebo treatment).

Time to Progression (TTP) at Primary Completion: FOLFIRI and mIFL every 6 weeks until disease progression [clinicaltrials_resource:4f4310473fc7df2b4944863dececd5b0]

Day 1 & 8: Irinotecan (125 mg/m2 IV over 90 minutes), LV (20 mg/m2 IV bolus), 5-FU (500 mg/m2 IV bolus). All chemotherapy cycles repeated every 3 weeks. Celecoxib/placebo treatment will commence on the same day as chemotherapy treatment (i.e. Day 1 of treatment on study). Celecoxib/placebo will be taken at a dose of 400 mg po BID [two times a day] (800 mg/day) and will continue daily without interruption (no rest period for celecoxib/placebo treatment).