Introduction Several recent retrospective studies have shown a survival gain for patients who received local surgery for metastatic breast cancer. However, data for elderly are not available; so the aim of this study was to assess survival differences according to local surgery for elderly patients (65 years and older) with metastatic breast cancer.

Methods All adult females diagnosed with metastatic breast cancer between 1990 and 2007 were selected from the Netherlands Cancer Registry. Relative survival was calculated as the ratio of survival observed and expected survival based on the corresponding (age, sex and year) general population. Relative Excess Risks of death were estimated using a multivariable generalised linear model with a Poisson distribution.

Results Overall, 10.782 patients were included; 50.4% was 65 years or older. Surgery was performed in 30% of the patients and decreased with increasing age (p<0.001). Over time, less patients received surgery (p<0.001). Relative survival was increasing in patients that received surgery, adjusted for potential confounders the Relative Excess Risks was 0.7 (95% CI 0.6 to 0.9; p<0.001) for 65–74 years old patients, 0.5 (95% CI 0.5 to 0.6); p<0.001) for patients aged 75–84 and 0.4 (95% CI 0.3 to 0.6; p<0.001) for the patients 85 and older. There were no differences in the independent prognostic factors associated with relative survival (age, grade, tumour size, lymph node involvement, type of metastases, additional treatment).

Conclusion This large retrospective study showed an improved relative survival for all elderly that received local surgery for metastatic breast cancer. However, large prospective randomised trials, including the elderly, are needed to confirm this association.