DISEASE CHARACTERISTICS:

• Histologically or cytologically confirmed adenocarcinoma of the pancreas

  • Stage II, III, or IV disease that is not amenable to resection with curative intent
• At least 1 bidimensionally measurable lesion with clearly defined margins by CT scan or MRI or by palpation with both diameters at least 2 cm
• No clinically significant third-space fluid collection (e.g., ascites or pleural effusions) NOTE: Fluid collections may be drained
• No documented brain metastases

PATIENT CHARACTERISTICS:

Age

• 18 and over

Performance status

• ECOG 0-2

Life expectancy

• At least 12 weeks

Hematopoietic

• Absolute neutrophil count at least 1,500/mm^3
• Platelet count at least 100,000/mm^3
• Hemoglobin at least 9 g/dL

Hepatic

• Bilirubin no greater than 1.5 times upper limit of normal (ULN)
• AST/ALT no greater than 3 times ULN (5 times ULN if liver metastases present)
• Alkaline phosphatase no greater than 3 times ULN (5 times ULN if liver metastases present)
• Endoscopic or radiologic stenting allowed for biliary obstructions (bilirubin must meet study requirements and AST/ALT and alkaline phosphatase must be no greater than 5 times ULN)

Renal

• Creatinine clearance at least 45 mL/min

Cardiovascular

• No unstable angina pectoris

Pulmonary

• See Disease Characteristics

Other

• No other malignancy within the past 5 years except carcinoma in situ of the cervix or adequately treated nonmelanoma skin cancer
• No active infection
• No other serious concurrent systemic disorders that would preclude study
• No uncontrolled diabetes mellitus
• No weight loss of 10% or more within the past 6 weeks
• No inability or unwillingness to take folic acid or vitamin B12 supplementation
• Not pregnant or nursing
• Fertile patients must use effective contraception during and for 3 months after study

PRIOR CONCURRENT THERAPY:

Biologic therapy

• No prior immunotherapy
• No prior biological therapy for pancreatic cancer
• No concurrent immunotherapy
• No concurrent routine colony-stimulating factors
• No concurrent stimulators of thrombopoiesis

Chemotherapy

• No prior chemotherapy for pancreatic cancer
• No prior fluorouracil for pancreatic cancer (including as a radiosensitizer)
• No other concurrent chemotherapy

Endocrine therapy

• No prior hormonal therapy for pancreatic cancer
• No concurrent hormonal therapy for cancer

Radiotherapy

• No prior radiation to whole pelvis
• Prior radiotherapy to less than 25% of bone marrow allowed
• At least 4 weeks since prior radiotherapy and recovered
• Concurrent palliative radiotherapy for small, painful metastases allowed

Surgery

• No concurrent surgery for cancer

Other

• At least 30 days since prior investigational agents or devices
• No other concurrent experimental medications (except thymidine)
• No other concurrent antitumor therapy
• No concurrent aspirin, salicylates, or other nonsteroidal anti-inflammatory drugs for 2-5 days before, during, and for 2 days after each dose of pemetrexed disodium