Key messages
– Breast surgery seems to help control cancer in the breast. It could also improve life expectancy for some women.
– However, breast surgery can lead to complications including death during surgery (rare), bleeding that requires a blood transfusion, infection, swelling of the arm (lymphoedema), changes in body image and a possible decline in quality of life.
What is metastatic breast cancer, and how common is it?
Metastatic breast cancer means the cancer has spread from the breast to other organs. Around 5 in 100 women to 10 in 100 women diagnosed with breast cancer already have cancer that has spread to other organs. While it cannot be cured, women with this cancer are living longer. Breast surgery is not typically part of the treatment for metastatic cancer, but we wanted to know if it might improve survival and quality of life.
What types of surgery are used to treat breast cancer?
Breast surgery can be:
– conservative surgery, where only part of the breast is removed, or
– radical surgery, where the entire breast is removed (called mastectomy).
Women who have a mastectomy may choose to have breast reconstruction during the same operation.
What did we do?
We looked for studies comparing breast surgery plus medical treatment (for example, medicines to kill the cancer (chemotherapy) and medicines prevent hormones that help the cancer grow (hormone therapy)) to medical treatment alone in women with metastatic breast cancer.
What did we find?
We found five studies involving 1368 women with metastatic breast cancer from Turkey, India, Austria, Japan and the USA. These women were monitored for periods ranging from three to 10 years.
Main results
Overall survival (length of time from entry into the study until death from any cause): breast surgery may not affect overall survival. However, there could be some benefit depending on the type of breast cancer. These findings are exploratory and not yet confirmed.
Quality of life: breast surgery might not affect quality of life, but more studies are needed to be certain.
Local control of disease: breast surgery helps control cancer in the breast, reducing the chance of it getting worse in that area.
Spread to other organs: breast surgery does not appear to prevent the spread of cancer to other parts of the body.
None of the studies reported survival measurements specifically related to breast cancer itself (as opposed to overall survival).
Deaths at 30 days after surgery (toxicity): breast surgery did not increase the risk of death within 30 days after surgery.
What are the limitations of the evidence?
We are confident that breast surgery helps control the disease in the breast. We are less confident about its effects on survival, spread to other organs, quality of life and toxicity. Our confidence in these results is limited because the studies were small and varied widely. Also, the studies used different criteria for choosing when to perform the surgery, and they reported results at different times. Further research might change our results.
How up to date is this evidence?
This review updates our previous review with evidence up to April 2023.
Read the full abstract
Metastatic breast cancer is not curable, but women with this condition are living longer. While breast surgery is not typically part of the treatment for metastatic disease, retrospective studies suggest it might improve survival. These studies have limitations, including selection bias. A systematic review of randomised controlled trials is needed to assess the benefits and potential harms of breast surgery.
Objectives
To assess the benefits and harms of breast surgery in women with metastatic breast cancer.
Search strategy
We conducted searches on the Cochrane Breast Cancer Specialised Register, CENTRAL, MEDLINE (PubMed), Embase (OvidSP), World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov on 19 April 2023. We conducted searches of conference proceedings, and contacted study authors to identify additional studies.
Selection criteria
The inclusion criteria were randomised controlled trials of women with metastatic breast cancer at initial diagnosis comparing breast surgery plus systemic therapy versus systemic therapy alone. The primary outcomes were overall survival and quality of life. Secondary outcomes were progression-free survival (local and distant control), breast cancer-specific survival and toxicity from local therapy.
Data collection and analysis
Two review authors independently assessed studies for inclusion and conducted data extraction, risk of bias assessment, and GRADE assessment of the certainty of the evidence. We used the risk ratio (RR) to measure the effect of treatment for dichotomous outcomes, mean difference (MD) for continuous outcomes and hazard ratio (HR) for time-to-event outcomes. We presented 95% confidence intervals (CI) and used a random-effects model due to expected clinical or methodological heterogeneity among the included studies.
Main results
This is the first update of this review and includes three new studies and longer follow-up for two previously included studies. In total, we included five studies with 1368 women: 679 in the breast surgery plus systemic therapy group and 689 in the systemic therapy group. The median follow-up ranged from 3.5 to 10 years. The studies varied in randomisation timing and inclusion criteria. Three studies included women who responded to systemic therapy and excluded those with disease progression, while two included women with untreated metastatic breast cancer.
The evidence suggests that breast surgery does not improve overall survival in women with de novo metastatic breast cancer (HR 0.89, 95% CI 0.75 to 1.05; P = 0.09; 5 studies, 1368 women; moderate-certainty evidence, downgraded due to imprecision). Exploratory subgroup analyses suggest potential variation in this finding based on immunohistochemical profile. The addition of breast surgery to systemic therapy may result in a slight improvement in overall survival in women with luminal tumours (HR 0.82, 95% CI 0.69 to 0.96; P = 0.01; 4 studies, 841 women; moderate-certainty evidence), yet this was not observed in women with human epidermal growth factor receptor 2 (HER2)-positive or triple-negative breast cancer. Additional exploratory analyses based on menopausal status and the extent of metastases (i.e. bone-only or multiple sites) suggest that surgery may result in little to no difference in overall survival in these groups.
Breast surgery plus systemic therapy may not improve quality of life at six-month follow-up (MD 1.91, 95% CI −2.52 to 6.34; P = 0.40; 2 studies; low-certainty evidence), may give some temporary improvement at 18-month follow-up (MD 6.09, 95% CI 1.90 to 10.28; P = 0.004; 2 studies; low-certainty evidence), which may not be sustained at 24-month follow-up (MD 2.74, 95% CI −2.22 to 7.70; P = 0.28; 2 studies; low-certainty evidence).
Breast surgery reduces the risk of local disease progression (HR 0.43, 95% CI 0.32 to 0.58; P < 0.01; 4 studies, 1093 women; high-certainty evidence), but it is unlikely to improve distant progression-free survival (HR 1.19, 95% CI 0.86 to 1.66; P = 0.29; 3 studies; moderate-certainty evidence; downgraded one level due to serious imprecision).
An analysis for breast cancer-specific survival was not possible because the included trials did not report data on this outcome.
One study assessed toxicity where adding breast surgery to systemic therapy did not seem to have an effect on 30-day mortality (RR 0.99, 95% CI 0.14 to 6.90; 1 study, 274 women; low-certainty evidence, downgraded due to very serious imprecision).
Authors' conclusions
Evidence from five randomised controlled trials suggests that adding breast surgery to the treatment of de novo metastatic breast cancer improves local disease control. Breast surgery does not seem to improve overall survival. However, the effect could vary depending on the immunohistochemical profile; these findings are exploratory and are not definitive. Breast surgery might not affect quality of life, distant progression-free survival or toxicity.
