In 2009, 2 single-institution studies from the United States reported increasing mastectomy rates during the last decade. We have recently reported unilateral mastectomy trends from a European database and demonstrated a significant trend of decreasing mastectomy rates from 38.1 % in 2005 to 13.1 % in 2010. A recent study from the SEER registry in the United States confirmed a previously reported decrease in mastectomy rates from 40.1 % in year 2000 to 35.6 % in 2005, but showed a statistically significant increase in mastectomy rates up to 38.4 % in 2008. This report provides evidence that mastectomy trends may be in opposite directions in different geographical areas. The sharpest increase in mastectomy rates across all ages in the recent SEER study occurs right after year 2005, which interestingly corresponds with the time of publication of the meta-analysis by the EBCTCG that highlighted the importance of local control in breast cancer. The coincident timing raises the question of whether this evidence may have indirectly triggered an increase in mastectomy rates in the United States that would partially explain the observed trend, and more importantly, of whether an increase would be justified on this basis. Multiple factors influence the proportion between mastectomy and breast conservation, so it may be unreasonable to think of an optimal cutoff. There is not necessarily a right or wrong direction for mastectomy trends, but aiming to determine explanations for these differences may help provide a clearer insight of the decision-making process involved in the surgical management of breast cancer.