A Retrospective Study Evaluating the Impact of Loco-regional Surgery in Metastatic Breast Cancer at the Time of Initial Diagnosis

Abstract

Breast cancer is the most common malignant tumor among women worldwide. Despite the advances in the diagnosis and management of breast cancer, 6–10% of affected patients present metastatic breast cancer at diagnosis and 30–40% will develop metastases during the evolution of their disease. The appearance of metastases, as a sign of incurability, constitutes a major problem of care. The recent therapeutic strategies and emergence of new drugs have not only helped to extend the median survival time (around 30 months now) but also to improve the quality of patients’ lives. The mainstay of treatment in metastatic breast cancer is systemic therapy, which includes chemotherapy, endocrine therapy and targeted therapy. Traditionally, loco-regional treatment (surgery or radiotherapy) has been used only for control of fungation and bleeding. However, metastatic breast cancer patterns have undergone some changes with increasingly sensitive imaging modalities, resulting in potential stage migration. This allows clinicians to better identify metastatic breast cancer patients with an improved prognosis and the potential to benefit from a more aggressive loco-regional or systemic treatment approach. Despite the prevailing clear recommendation against non-palliative primary tumor surgery in metastatic breast cancer, removing the primary tumor has been associated with decreased overall mortality in several retrospective studies, with a hazard ratio for mortality of 0.65 (0.59–0.72) and 0.69 (0.63–0.77) according to two recent meta-analyses. However, all of the studies are retrospective in nature, and potentially suffer from case selection bias, with better prognosis patients being more likely to undergo primary tumor surgery. This bias cannot definitely be precluded by usual multivariable adjustment, and may thus contribute to the survival advantage found in patients undergoing primary tumor surgery. Our study analyzed retrospectively the impact of loco-regional surgery on the outcome of patients with breast cancer found to be metastatic at their initial diagnosis, and found a clear survival benefit in the patients underwent surgery for their primary breast tumor. The results of the current study contribute to the growing body of literature addressing the question of whether surgical resection of the primary tumor in patients presenting de novo with stage IV disease improves survival. Findings from this and other studies provide support for a prospective, randomized trial to more definitively test the hypothesis that better control of local disease in stage IV breast cancer patients will improve survival. Other important questions that should be addressed are the optimal timing of surgery, the optimal chemotherapy regimen, and methods of and indications for resection of site(s) of metastasis. We do not at present recommend ‘routine’ breast surgery or definitive local treatment in women with known metastatic breast cancer receiving standard palliative treatments.