The primary objective of the trial is to identify the dose of gemcitabine given as a 2-hour intravenous (iv) infusion that can be administered in combination with ZD1839 250 mg once daily and a standard course (45 Grays [Gy]) of radiotherapy in patients with locally advanced, unresectable pancreatic cancer.

Inclusion Criteria:

• Histologically confirmed pancreatic cancer (aspiration biopsy by fine needle [PAAF] by USE or biopsy guide by ECO-CT). It is mandatory the diagnostic by USE and will recommend the aspiration biopsy with this technique
• Tumoural volume by TAC < 500 cc
• Aged 18 to 75 years inclusive
• Eastern Cooperative Oncology Group (ECOG) performance status (PS) £ 1
• Life-expectancy of more than 12 weeks
• Women of child-bearing potential must be willing to practice reliable methods of birth control to prevent pregnancy

Exclusion Criteria:

• Previous radiotherapy or chemotherapy for malignant disease
• Other co-existing malignancies or malignancies diagnosed within the last 5 years with the exception of basal cell carcinoma or cervical cancer in situ
• In the opinion of the investigator, any evidence of severe or uncontrolled systemic disease (e.g. unstable or uncompensated respiratory, cardiac, hepatic or renal disease)
• Absolute neutrophil count (ANC) less than 1.5 x 109/litre (L), platelets less than 100 x 109/L or haemoglobin less than 9 mg/dL; Prothrombin time (PT) less than 50%; Serum bilirubin greater than 2.5 times the upper limit of reference range (ULRR; Creatinine clearance less than 45 mL/min; ALT or AST greater than 2.5 times the ULRR
• Active dermatoses (e.g. psoriasis, eczema)
• Concomitant use of phenytoin, carbamazepine, barbiturates, rifampicin, or drugs with known corneal toxicity
• Known, severe hypersensitivity to ZD1839 or any of the excipients of this product