How is breast cancer treated with medicines

Medicines act on cancer cells, including those which have spread. We know that in some women there are small numbers of cancer cells that have spread beyond the breast but cannot be detected by scans. Medicines can kill these cells or prevent them from growing for many months and years after surgery with or without radiotherapy. This is called adjuvant treatment. In some patients with larger but operable breast cancers, the medicines can be used before surgery to shrink the cancer. This allows some women who would initially have required a mastectomy to be treated by less extensive surgery. If the cancer has already spread at the time it is first diagnosed or a patient who is treated for early breast cancer develops a recurrence of the cancer at some other site in the body, then the only practical way of treating these two groups of patients is by medicines. The medicines for treating breast cancer fall into two groups: hormones and chemotherapy. Whether the patient receives hormone therapy or chemotherapy will depend on the size of the tumour, type of tumour (including the grade) and whether the tumour has spread to involve the lymph glands.