Radiation Therapy and Chemotherapy in Treating Patients With Cancer of the Pancreas or Stomach

OBJECTIVES: I. Determine the maximum tolerated dose of gemcitabine and cisplatin that can be
administered during a standard course of radiation therapy for patients with unresectable or
locally recurrent pancreatic and gastric cancer. II. Describe the tolerance of gemcitabine,
cisplatin, and radiation therapy in this patient population. III. Seek preliminary evidence
of the therapeutic activity of this regimen in this patient population as measured by
survival.

OUTLINE: This is a dose escalation study. Patients undergo radiotherapy to the tumor and
lymph nodes, followed by a decrease in radiotherapy to the tumor alone. Radiation therapy is
administered for a total of 5.5 weeks. Patients receive intravenous gemcitabine twice weekly
on Tuesday and Friday over the first 3 weeks of radiotherapy. Cisplatin is administered
intravenously twice weekly following gemcitabine therapy. Three patients are treated at each
dose level. Dose escalation does not occur until all patients at a given dose level have
completed radiotherapy and returned for a 4 week follow up. The dose limiting toxicity (DLT)
is defined as the dose at which at least 2 of 6 patients experience unacceptable toxic
effects. The maximum tolerated dose is defined as the dose at which no more than 1 of 6
patients experiences DLT. Patients exhibiting stable disease remain on therapy until disease
progression or intolerable toxic effects. Patients experiencing toxic effects and no disease
progression are retreated at a lower dose. Patients are followed every 3 months for the
first 2 years then every 6 months for the next year.

DISEASE CHARACTERISTICS: Histologically proven unresectable (including incomplete
resections) or locally recurrent pancreatic or gastric cancer No evidence of metastases
outside of the planned radiation field No cystadenocarcinoma of the pancreas or pancreatic
tumors of neuroendocrine origin

PATIENT CHARACTERISTICS: Age: 18 and over Performance Status: ECOG 0-1 Life Expectancy:
Not specified Hematopoietic: Absolute neutrophil count at least 2,000/mm3 Platelet count
at least 100,000/mm3 Hepatic: Bilirubin within normal limits Alkaline phosphatase no
greater than 3.0 times upper limit of normal (ULN) AST no greater than 3.0 times ULN
Renal: Creatinine no greater than 1.3 times ULN Other: Not pregnant or nursing Fertile
patients must use effective contraception No significant infection or medical illness No
significant nausea or vomiting At least 1200 calories per day of oral nutrition

PRIOR CONCURRENT THERAPY: Biologic therapy: No prior or concurrent biologic therapy
Chemotherapy: No prior or concurrent chemotherapy Endocrine therapy: Not specified
Radiotherapy: No prior radiotherapy (except focal fields for skin cancer that do not
overlap with planned radiotherapy fields) Surgery: At least 21 days since laparotomy
surgery