Mastectomy in precision oncology era: myth or reality?

We read with great interest the study by van Maaren et al. recently published in Lancet Oncology (1). This study, conducted on a large Dutch population, shows that breast conservative surgery (BCS) associated with radiotherapy is at least comparable in terms of overall survival to mastectomy. Interestingly, in the subgroup of patients with early stage disease thus with lower prognostic risk (pT1N0), the study reports that mastectomy is even detrimental on survival compared to BCS combined with radiotherapy. Apparently, the lack of exposure to radiation therapy in patients who underwent mastectomy could explain the unfavorable prognostic impact. Although, paradoxically, the benefit of radiation treatment is lost in the subgroups with worst prognosis stage (pT2N0, pT1-2N1), in which the impact of such treatment is expected to be superior. The Authors defend these results in the light of the statistical significance of these data in the multivariate analysis, which includes various factors that may influence the prognosis.