141IN - The Role of Surgery for M1 Breast Cancer

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ABSTRACT M1 breast cancer is regarded as an incurable disease. Therefore, surgery has been considered as beneficial only for palliative purposes, like toilet mastectomy for ulceration, bleeding or pain. However, several recent studies show, that patients who have received elective surgery as a part of their treatment live longer than those with surgical treatment. The biological basis behind the phenomenon has been speculated. Surgery leads to decreased tumour burden, lower levels of circulating tumour cells and maybe beneficial immunological responses. On the other hand, majority of the studies reporting longer survival in operated patients are retrospective. Patients who have received surgical treatment have been younger, have received more systemic treatments, especially chemotherapy and anti-HER2 agents, have had fewer metastatic sites or asymptomatic metastases only. Therefore, the observed longer survival in operated patients may be just due to selection bias. Moreover, many of these studies suffer also other methodological shortcomings. A few randomized trials have been launched to clarify if surgery really prolongs survival in M1 breast cancer, including the Turkish MF 07-01 protocol, the Indian trial from Tata Memorial Centre, the Dutch SUBMIT trial and the Japanese JCOG1017 trial. The results from the two first mentioned trials were reported in SABCS 2013. In the Indian trial, surgery was not associated with survival benefit, neither in the entire study population of 350 patients nor in any of the evaluated subgroups. Neither the Turkish trial was able to show survival benefit after surgery in the entire study population (N = 278) during a median follow-up of 18 months. The authors also reported numerous subgroup analyses, suggesting possible survival benefit in younger patients, in patients with bone metastases only, especially in those with solitary bone metastasis. Patients with initial surgery and multiple liver or pulmonary metastases, in turn, did worse than those with systemic treatment only. However, these subgroup analyzes were unplanned and may therefore suffer from multiple testing. In conclusion, the results from the two reported randomized trials were mainly discouraging and do not indicate elective surgical treatment in patients with M1 breast cancer outside trials. Disclosure: The author has declared no conflicts of interest.