A Phase II Randomised, Double-Blind, Stratified, Multi-Centre Trial Comparing the Nolvadex 20 Mg And Placebo Combination To The Nolvadex 20 Mg and ZD1839 (IRESSA™) 250 MG Combination In Patients With Metastatic Breast Cancer And Estrogen Receptor (ER) and/or Progesterone (PR) Positive Tumours

Inclusion Criteria:

- Histologically confirmed metastatic adenocarcinoma of the breast (seeTNM staging
Appendix I) that is ER and/or PR positive as determined in local laboratories at each
investigator site (central verification of ER status will be performed after the
patient starts treatment

- A tissue block from either the metastatic or primary tumor site is required.

- WHO performance status (PS) 0-2

- Patients must not be pregnant or breast-feeding. A negative pregnancy test is
required within 7 days prior to randomization if pre- or peri-menopausal.
Postmenopausal patients are defined as:

- natural menopause with last menses > 1 year ago,

- radiation induced oophorectomy with last menses > 1 year ago,

- chemotherapy induced menopause with 1 year interval since last menses, or

- serum FSH and LH and plasma estradiol levels in the postmenopausal range for the
institution.

- bilateral oophorectomy

Exclusion Criteria:

- Patients cannot be on hormone replacement therapy or received prior chemotherapy for
metastatic disease.

- Patients previously treated with a Tyrosine Kinase inhibitor or have evidence of an
active interstitial lung disease are not eligible.

- Treatment with LH-RH analog.

- Laboratory values as follow Bilirubin >1.5 times upper limit of normal ULN, alanine
amino transferase (ALT) or aspartate amino transferase (AST) >2.5 times the ULN if no
demonstrable liver metastases, or >5 times the ULN in the presence of liver
metastases

- Bone marrow function: WBC <1500 mm3