Range of treatments

In high-income countries, most breast cancers are diagnosed early (stages I, II or IIIA) when all detected cancer cells are in the breast or nearby lymph nodes and can be removed surgically. Most women diagnosed with early breast cancer now survive, but in some women undetected cancer cells remain after surgery. These cells can start to proliferate, sometimes many years later, resulting in a recurrence of the original breast cancer. ‘Adjuvant’ treatments such as radiotherapy, chemotherapy and hormonal therapy may be used after surgery to try to kill or suppress these cancer cells.

Radiotherapy and chemotherapy are ‘cytotoxic’ treatments that act on cancer cells but can also damage healthy cells. Early clinical trials established that the benefits outweigh the harms for most women and recent trials have aimed to identify more effective and/or less toxic radiotherapy and chemotherapy treatments.

Hormonal therapy is used to treat or prevent breast cancer in addition to cytotoxic treatments. Most breast cancers express the oestrogen receptor (ER) and are driven by the female hormone oestrogen. These ‘ER-positive’ cancers can be treated by greatly reducing natural oestrogen levels, by removing a woman’s ovaries or stopping them from producing oestrogen with an aromatase inhibitor (AI), which blocks the pathway through which oestrogen is produced, or by blocking the oestrogen receptor, with a selective oestrogen receptor modulator such as tamoxifen.

A substantial minority of breast cancers can be treated effectively by blocking other receptors (eg, with trastuzumab, which blocks the Her2-neu receptor). As we learn more about the complex biology of breast cancer, other biological therapies that attack the breast cancer stimulation pathway are being developed and tested in clinical trials.