Does removal of the primary tumor improve survival in stage IV breast cancer?

This analysis of several case studies evaluated whether removal of primary tumor in stage IV breast cancer helps improve overall survival.

In stage IV (metastatic) breast cancer, 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 breast cancer usually aim at lowering the extent of metastases (spreading of cancer cells to distant organs), extending survival and improving patients’ quality of life. The general belief is that in stage IV breast cancer, survival depends on the extent of metastases and that the local removal of the primary cancer does not improve the survival rate. At the same time, surgical removal of the primary tumor has shown to improve survival in other types of cancer, such as skin, kidney or bowel cancer. The present study aimed to determine whether removal of the primary cancer has any effect on survival in breast cancer patients.

For this research, the authors analyzed several studies that evaluated survival rates in stage IV breast cancer patients after removal of the primary tumor. Overall, data from ten studies were included, where 28693 patients with stage IV breast cancer participated. Of these, 15162 patients underwent surgery to remove the primary cancer, while 13531 received systemic (whole body) treatment only, such as chemotherapy or hormonal therapy. Of the patients treated with surgery, 61% underwent a mastectomy (removal of the whole cancer-affected breast) and 39% underwent breast conserving surgery or a lumpectomy (removal of the cancerous lump only). Results showed that the survival rate 3 years after the treatment was 40% in the surgery-treated group compared to 22% in patients who did not undergo surgery. However, patients treated with surgery tended to have smaller tumors and fewer metastases compared to patients who did not have surgery.

In summary, stage IV breast cancer patients who underwent surgical removal of the primary tumor had significantly higher survival rates compared to patients treated with systemic therapies only. However, this was applicable to only a select group of patients, with a relatively good health status before the operation.

A drawback for this study stems from the fact that it analyses studies that have been done in the past (retrospective studies), rather than following patients throughout their treatment and determining their outcomes (prospective studies). Future prospective studies are needed in order to determine the actual effects on survival of surgical removal of the primary tumor in stage IV breast cancer patients.