Inclusion Criteria:

- Histologic confirmation of esophageal carcinoma (squamous or adenocarcinoma) or
gastric adenocarcinoma.

- Surgically unresectable disease and/or metastatic disease.

- No prior chemotherapy therapy.

- Life expectancy > 12 weeks.

- Patients must have the ability to take and retain oral medications.

- Patients must have Eastern Cooperative Oncology Group (ECOG) performance status of 0,
1, or 2 (Karnofsky Performance Status [KPS] ≥50%).

- Patients must have measurable disease by Response Evaluation Criteria in Solid Tumors
(RECIST) criteria and computerized tomographic scan performed within 28 days prior to
registration.

- Organ system function assessed within 7 days prior to registration and within the
following parameters:

- Absolute neutrophil count ≥1500/mL;

- Platelet count ≥100,000/mL;

- Hemoglobin level ≥10.0 gm/dL;

- Serum creatinine ≤1.5 x IULN (Institutional Upper Limits of Normal); OR Measured
creatinine clearance ≥60 mL/min;

- AST (SGOT) or ALT (SGPT) ≤ 2.5 x IULN (unless the liver is involved by tumor, in
which case it must be ≤5.0 x IULN);

- Total bilirubin ≤1.5 x IULN.

- Understanding of the subject of the potential and unknown teratogenic risk, as well
as their willingness to practice birth control. Should a pregnancy occur while a
subject, either father or mother, is receiving study medication, the subject should
inform the doctor immediately.

- Aged 18 years or older

- Provision of written informed consent

- For patients with locally advanced disease, subjects must be evaluated by a radiation
oncologist prior to study entry, and judged that radiation therapy is not indicated
in the subjects therapy.

Exclusion Criteria:

- Prior treatment with EGFR-inhibiting agents, chemotherapy, or radiotherapy for
esophagogastric carcinomas.

- Patients must not be receiving any other investigational agents. Use of
erythropoietin is allowable. Secondary prophylaxis with granulocyte colony
stimulating factor (G-CSF) (Filgrastim) is allowable. The use of
granulocyte-macrophage colony stimulating factor (GM-CSF) (Sargramostim) is not
allowed on this protocol.

- Uncontrolled brain metastases.

- Patients must not have uncontrolled intercurrent illness at the time of registration
including, but not limited to, ongoing or active infection, symptomatic congestive
heart failure, unstable angina, pectoris, cardiac arrhythmia, or psychiatric
illness/social situations that would limit compliance with study requirements.

- Patients must not have current New York Heart Association Class III or IV heart
disease.

- Known human immunodeficiency virus (HIV) infection.

- Pregnant or breast-feeding women.

- Patients who have had prior malignancies, except non-melanoma skin cancer (basal or
squamous cell carcinoma) are not eligible for this study; unless greater than 5 years
has passed since the event.

- Known severe hypersensitivity to ZD 1839 or any of the excipients of this product.

- Concomitant use of phenytoin, carbamazepine, barbiturates, rifampicin, phenobarbital,
or St. John's Wort.

- Treatment with a non-approved or investigational drug within 30 days before Day 1 of
trial treatment.

- Incomplete healing from previous oncologic or other major surgery.

- Serum creatinine level greater than Common Toxicity Criteria (CTC) grade 2.

- Any evidence of clinically active interstitial lung disease. Subjects with chronic
stable radiographic changes who are asymptomatic need not be excluded.