Does removal of the breast tumor improve survival in stage IV breast cancer with bone metastasis?

This study investigated the effects of the removal of the breast tumor in patients newly diagnosed with stage IV breast cancer and bone metastasis only. The data showed that removal of the breast tumor improved survival outcomes and decreased the recurrence rates in these patients.

In stage IV breast cancer (BC), the cancer spreads beyond the breast and nearby lymph nodes, to other organs and tissues of the body, such as the lungs, liver, bones, or brain. Treatments for stage IV BC usually aim at lowering the extent of metastases (spreading of cancer cells to distant organs). Systemic therapy (where the drug travels through the blood to cells all over the body) like chemotherapy or hormonal therapy is usually the main treatment for these patients.

The general belief is that in stage IV BC, survival depends on the extent of metastases and that the local removal of the breast tumor does not improve the survival rate. At the same time, surgical removal of the breast tumor has shown to improve survival in other types of cancer, such as skin, kidney, or bowel cancer. It is unknown whether removal of the breast tumor has any effect on survival in patients newly diagnosed with BC spread to the bones.

This study involved 505 women with newly diagnosed stage IV BC. They were divided into 2 groups. Group 1 included 240 women who received systemic treatment (ST) only. Group 2 included 265 women who received locoregional treatment (LRT). Patients in group 2 also received ST before or after LRT. The average follow-up time was 34.9 months in group 2 and 33 months in group 1.

At follow-up, local progression of the tumor was seen in 6.7% of the patients of group 2 compared to 16.2% of group 1. The 5-year survival without cancer spreading more was 43% in group 2 and 20% in group 1. The 5-year survival without cancer worsening in the breast area was 78% in group 2 and 52% in group 1.

The 5-year overall survival rate was 72% in group 2 and 33% in group 1. Patients who received LRT were 60% more likely to survive compared to those who received ST.

This study concluded that surgical removal of the breast tumor improved the outcomes of patients newly diagnosed with stage IV BC spread to the bones.

Patients were not randomly assigned to one of the groups. Patients in the LRT group were younger than in the ST group. This might have influenced the results.