Primary Tumor Resection in Stage IV Breast Cancer: Consistent Benefit, or Consistent Bias?

Excerpt

The recommended primary treatment approach for women with metastatic breast cancer and an intact primary tumor is the use of systemic therapy, with local therapy for the primary tumor reserved for palliation of symptoms. The past 6 years have seen an accelerating pace of publication of studies examining survival outcomes relative to the surgical resection of the intact primary tumor in women with metastatic breast cancer.1‐4 These show that in fact about half the women presenting with de novo metastatic disease undergo resection of the primary tumor and suggest that women so treated survive longer than those treated without resection. In analyses that adjust for tumor burden (number of metastatic sites), types of metastases (visceral, nonvisceral), and the use of systemic therapy, the hazard of death is reduced by 40–50% in women receiving surgical treatment of the primary tumor. Thus, five retrospective studies including the report by Fields et al.5 in the present issue of the Annals of Surgical Oncology, present us with consistent evidence that either surgical therapy of the primary tumor has a substantial survival benefit in women with metastatic breast cancer, or there is a strong and consistent selection bias driving the use of surgery in women who have more favorable profiles (i.e., younger age, smaller tumor burden, better access to care). It is also possible that surgery is a surrogate indicator of more aggressive therapy overall, including more aggressive systemic therapy, which translates into better survival. All authors acknowledge the problem of selection bias in the interpretation of these data, and all advocate for a randomized trial to settle this question. …