Inclusion Criteria:

- Be at least 18 years of old.

- Have been diagnosed with breast cancer

- At least one year disease-free interval after initial treatment.

- Have pre-study laboratory tests that are within the requirements of this study.

- Be able to visit the doctor's office weekly during the treatment period.

Exclusion Criteria:

- To be pregnant or breastfeeding.

- To be currently taking aspirin or aspirin- like medicine and unable to stop for a few
days during each cycle of therapy.

- To have received prior chemotherapy for the treatment of metastatic cancer. Patients
may have received prior hormonal treatment.

- To have another illness that your doctor thinks would make you unable to participate.

- To be unable or not willing to take folic acid and vitamin B12.