A Randomized Trial of Avastin + Gemcitabine + 5-Fluorouracil (5FU)/Folinic Acid Versus Avastin + Oxaliplatin + 5FU/Folinic Acid in Metastatic Colorectal Cancer

Inclusion Criteria:

* Patients must have a histological or cytological diagnosis of the colon or rectum with Stage III unresectable or Stage IV disease.
* Urinalysis or Urine dipstick for proteinuria of less than 1+ (i.e. either 0 or trace). If urine dipstick is greater than 1+, the 24 hour urine protein must demonstrate less than 500 mg of protein in 24 hours to allow participation.
* No prior chemotherapy, immunotherapy, or hormonal treatment for metastatic disease is acceptable. However, one prior neo-adjuvant or adjuvant treatment is acceptable, including Capecitabine, Camptothecin-11 (CPT-11), 5 Fluorouracil/Leucovorin (5FU/LV) or Radiation containing regimens, (but no Oxaliplatin), and only if progression \> 6 months since last adjuvant treatment.
* Prior radiation therapy, including radiation to the whole pelvis, is allowed (Cristy and Eckerman 1987) and patients must have recovered from the acute toxic effects of the treatment prior to study enrollment. Prior palliative radiation therapy given to a non-measurable diagnostic site is acceptable if given \> 4 weeks prior to treatment or if other non-irradiated measurable disease is present.
* No known central nervous system (CNS) metastasis.

Exclusion Criteria:

* Histology other than adenocarcinoma
* Tumors that demonstrate free perforation as manifested by free air or free fluid in the abdomen. Patients with walled-off perforation are eligible.
* Gastroduodenal ulcer determined as active by endoscopy.
* Invasive procedures defined as follows; major surgical procedures, open biopsy, or significant traumatic injury within 28 days prior to randomization, anticipation of need for major surgical procedure during the course of study, core biopsy or other minor procedure within 7 days prior to registration.
* Following cardiac condition; New York Heart Association (NYHA) Class III or IV, myocardial infarction (MI) within 6 months, unstable angina within 6 months and current symptomatic arrhythmia.