680 surgery was 67%, in the US only 8.8% had no surgery and in Germany all patients in this age category received breast surgery. The ﬁndings in the US are consistent with a recently published study from the US in which 98% of all T1 or T2 breast cancer patients aged C65 years received at least some surgery [17]. International studies comparing the percentage of breast cancer patients who do not receive surgery are scarce. Most observational studies of survival excluded patients who did not have any surgical treatment, but the few retrospective studies that did include non-sur- gically treated patients showed poor overall and lower breast cancer-speciﬁc survival for these patients [13, 17– 19]. Many descriptive studies from different countries have also showed less extensive surgical treatment for elderly women with early stage breast cancer compared with younger patients [2, 3, 7, 11, 12]. Radiotherapy An overview of clinical trial data has shown that BCS should be followed by radiotherapy to achieve results comparable with mastectomy in terms of recurrence and survival [4]. In some elderly women BCS without radiation may be used to minimize potential treatment-related complications. However, the value of RT after BCS in elderly breast cancer patients is still subject of debate, since some studies suggest that radiation may be safely omitted for low-risk tumors in women over age 70 [20, 21]. This study shows that the proportion of women who received RT after BCS decreased with age. This trend was found in all participating countries, although speciﬁc proportions vary. Notable are the high percentages of elderly patients that received RT after BCS in Switzerland (79%) and Germany (MCR 80%). Possibly, for Switzerland, high accessibility of health services could partly explain this ﬁnding. For the selected German region (Munich), a pre- vious study demonstrated that this speciﬁc region has a higher percentage of BCS for early stage breast cancer than ﬁve other regions in Germany, so this region may not be completely representative for the whole country [22]. Also interesting are the differences in breast surgery between the Netherlands and Ireland (both national databases). Both countries have a high proportion of patients that receive no breast surgery although it is higher in Ireland. The pro- portion of BCS decreases with age in the Netherlands but increases in Ireland; the proportion of adjuvant RT decreases with age in both countries. This remarkable difference in loco-regional therapy did not inﬂuence sur- vival in any way. Information concerning loco-regional recurrences, not routinely collected by most cancer regis- tries, could add some information to these comparisons and should be collected when possible in the future. 123 Breast Cancer Res Treat (2012) 132:675–682 Axillary surgery In all participating countries the proportion of women in whom axillary surgery was not performed increased with age, a ﬁnding consistent with another observational study [23]. The largest proportion was found in Ireland, directly followed by the US, Portugal and the Netherlands. Ger- many stands out on this topic; only 1.4% of the elderly breast cancer patients did not undergo any form of axillary surgery. Axillary staging is part of some guidelines, and these ﬁndings suggest that guideline adherence decreased with increasing age. However, several randomized and non-randomized studies showed very low rates of axillary recurrences and comparable disease-free and overall sur- vival between clinical node-negative elderly breast cancer patients with and without axillary surgery [24, 25]. Strengths and limitations One of the strengths of this comparison is the large number of patients and the population-based datasets that included all elderly patients. This facilitated comparison of treat- ment strategies in countries with similar health systems by using country as an instrumental variable. A limitation of this study is that systemic treatment information was not available for all countries. However, available data indicate that rates of hormonal therapy (HT) were high: for example, among non-surgically treated patients, the proportion receiving HT was 85% in the Netherlands and 69% in Ireland. However, it is question- able if HT can replace surgery in elderly patients. Trials in which women aged C70 were randomized to have surgery or HT do not show signiﬁcant better overall survival for surgery compared to HT alone, although risk of recurrence is signiﬁcantly larger when operable breast cancer in elderly is treated by tamoxifen alone [26, 27]. Another limitation of this study might be that information con- cerning the extent of ‘‘clear margins’’ after BCS was not available. Another limitation of the study could be differences in data collection between the participating registries and the absence of national data for several countries (only the Netherlands, Belgium, and Ireland are national cancer registries). In countries with regional data, the regions may not be perfectly representative of the whole country. Also the small number of patients included for Portugal may not be representative and in some categories, numbers were insufﬁcient to draw conclusions about treatment. Finally, the years of available data were not completely overlap- ping, and thus changes in treatment patterns over time could inﬂuence our ﬁndings.