Gemcitabine Hydrochloride With or Without Bevacizumab in Treating Patients Who Are Undergoing Surgery for Pancreatic Cancer

DISEASE CHARACTERISTICS: Histologically or cytologically confirmed adenocarcinoma of the pancreas No evidence of distant metastasis on laparoscopy No superior mesenteric artery or thrombosed superior mesenteric vein involvement Superior mesenteric vein or portal vein involvement allowed Evidence of a pancreatic mass by radiographic or endoscopic examination PATIENT CHARACTERISTICS: Performance status ECOG 0-1 Life expectancy Not specified Hematopoietic WBC ≥ 2,500/mm^3 Absolute neutrophil count ≥ 1,250/mm^3 Platelet count ≥ 100,000/mm^3 Hepatic Hepatitis B surface antigen negative Hepatitis C virus negative No history of hepatic cirrhosis Renal Creatinine ≤ 2.0 mg/dL Proteinuria negative or trace by urinalysis OR Protein < 1 g on 24 hr urine collection No active gross hematuria Cardiovascular No severe congestive heart failure No active ischemic heart disease No ischemic changes on a cardiac thallium stress test No uncontrolled hypertension (i.e., blood pressure ≤ 150/100 mm Hg despite antihypertensive therapy) No active coagulation disorder Pulmonary No active gross hemoptysis Other Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception during the adjuvant therapy part of trial HIV negative No active infection No wound healing problem from recent invasive procedure No significant history of medical illness that would preclude patient from undergoing an operative procedure No other malignancy requiring systemic therapy PRIOR CONCURRENT THERAPY: Biologic therapy Recovered from prior immunotherapy for pancreatic cancer No prior bevacizumab Chemotherapy Recovered from prior chemotherapy for pancreatic cancer No prior gemcitabine hydrochloride Endocrine therapy Recovered from prior hormonal therapy for pancreatic cancer Radiotherapy Recovered from prior radiotherapy for pancreatic cancer No prior radiotherapy to the pancreas Surgery No prior definitive resection of the primary pancreatic tumor Prior surgery, other than resection of the primary tumor, allowed Other More than 3 weeks since prior systemic therapy for this cancer No concurrent therapeutic anticoagulation causing elevated PT or PTT