Review question

In women with metastatic breast cancer (when the cancer has spread to other parts of the body), what is the effectiveness of breast surgery (mastectomy: removal of the whole breast including nipple and areola, or lumpectomy: removal of the tumour and breast tissue around it but preserving the nipple and areola) combined with medical treatment (such as chemotherapy and hormone therapy) compared to medical treatment alone?

Background

Metastatic breast cancer is considered an incurable disease with poor prognosis, although some women can live for many years. It is traditionally treated only with medical treatment. Breast surgery was believed to be palliative and performed only to relieve symptoms such as local bleeding, infection, or pain. With the development of new medications, women with metastatic breast cancer are living longer, and breast surgery could benefit this group of women. Retrospective data (i.e. data from types of studies other than randomised controlled trials that are more likely to suffer from bias) suggest that breast surgery could improve the survival of women with metastatic breast cancer.

Study characteristics

The evidence is current to February 2016. We included only randomised clinical trials, as they are considered to be the best type of scientific study to answer questions about treatment, that compared the survival of women undergoing breast surgery combined with medical treatment versus medical treatment alone. We identified and included two randomised controlled trials involving a total of 624 women: 311 women underwent breast surgery plus medical treatment, and 313 women only received medical treatment.

Key results

The review authors are uncertain whether breast surgery improves overall survival as the quality of the evidence has been assessed as very low. The included studies did not report any information relating to quality of life. Breast surgery may improve the control of local disease but it probably worsened control at distant sites. The two included studies did not measure breast cancer-specific survival. Toxicity from local therapy appeared to be the same in the group undergoing breast surgery combined with medical treatment and in the group receiving only medical treatment.

What does this mean?

It is not possible to make definitive conclusions about the benefits of breast surgery associated with medical treatment for women with metastatic breast cancer. The decision to perform surgery in such cases should be individualised and shared between the physician and the patient, considering the potential risks and benefits involved in this choice. The inclusion of results of ongoing trials involving women with these characteristics in the next update of this review will help to decrease existing uncertainties.