Breast Cancer Res Treat (2012) 132:675–682 for any reason, were positioned in the mastectomy group. Receipt of radiation in addition to BCS was also assessed. Axillary surgery (either sentinel node biopsy or axillary lymph node sampling or dissection) was documented (yes/ no). Descriptive statistics were used, as only aggregated tables were compared, to assess the proportion of patients receiving each treatment; where possible percentages were compared using the v2 test. A P value of \0.05 was con- sidered statistically signiﬁcant. Relative survival was calculated by the Ederer II method as the ratio of the survival observed among the cancer patients to the survival that would have been expected based on the corresponding (age, sex, and year of diag- nosis) general population. National life tables for each country were used to estimate expected survival. In all countries and regions, vital status was established either directly from the patient’s medical record or through linkage with the municipal or national population regis- tries. The SEER database links with the National Death index, which also provided causes of death, and disease- speciﬁc survival was calculated for patients treated in the US. Survival of Irish patients was mainly based on linkage to national mortality data, sometime supplemented with clinical information on date of death. For the survival analysis age was categorized as 65–74, 75–84, and C85. 677 Results Overall, 204.885 patients were included in the study. Characteristics of the populations are shown in Table 1. Age distribution was similar (P = 0.9) across participating countries. Stage distribution among European countries was comparable (P = 0.5), however, US patients more frequently had stage I disease (P = 0.06). Grade distribu- tion was signiﬁcantly different between the countries (P \ 0.001). Breast surgery Figure 1 shows the proportions of patients who did not receive breast surgery in the several countries by age. The proportion of women not undergoing breast surgery varies among countries (P \ 0.001) from 0.5% (MCR Germany) to 13.4% (Ireland). Overall, the proportion of patients who did not receive surgery increased with age. In the lowest age categories (65–69 and 70–74), proportions of patients without breast surgery were small (\5%) in all countries (difference between countries were small but signiﬁcant P \ 0.001). As age increases, larger differences in the omission of breast surgery become apparent (again P \ 0.001). In the US and Germany, in particular, Table 1 Characteristics of the populations by country Country Netherlands Belgium Switzerland Germany (MCR) Ireland Cases % Cases % Cases % Cases % Cases % Portugal (ROR-Sul) Cases % Age 65–69 10,162 28.6 70–74 9,636 27.1 75–79 6,982 19.6 80–84 5,260 14.8 85–89 2,687 7.6 90? 853 2.4 Stage I 15,894 44.7 IIA 13,288 37.3 IIBb 6,398 18.0 Grade 1 5,316 14.9 2 12,036 33.8 3/4 7,383 20.8 Missing 10,845 30.5 Total 35,580 100 33.1 25.8 21.3 12.9 4.8 2.2 47.2 42.9 9.9 2,337 1,818 1,503 907 340 153 3,331 3,028 699 1,193 16.9 2,983 42.3 2,259 32.0 623 8.8 7,058 100 465 365 273 171 100 50 657 530 237 314 794 253 63 1424 32.1 25.2 18.8 12.0 7.2 3.5 46.0 37.2 16.6 22.0 55.8 17.7 4.4 100 4,539 3,077 2,322 1,152 376 73 5,471 4,120 1,948 1,503 6,888 2,842 306 11,539 39.3 26.7 20.1 10.0 3.3 0.6 47.4 35.7 16.9 13.0 59.7 24.6 2.7 100 30.0 26.5 20.9 14.6 6.3 1.7 34.2 43.3 22.5 1,295 1,142 901 631 271 72 1,476 1,867 969 476 11.0 1,890 43.8 1,188 27.6 758 17.6 4,312 100 40 40 23 13 7 1 55 47 22 17 81 11 15 124 32.3 32.3 18.5 10.5 5.6 0.8 44.4 37.9 17.7 13.7 65.3 8.9 12.1 100 MCR Munich cancer registry, ROR-Sul Portugal South Regional Cancer Registry a P = 0.06 including US, but P = 0.5 among European countries only b But excluding T3N0M0 USA Cases 36,629 35,109 33,279 23,592 11,678 4,561 90,402 39,109 15,337 % 25.3 24.2 23.0 16.3 8.1 3.1 62.4 27.0 10.6 P value 0.9 0.06a 36,182 25.0 \0.001 61,178 42.2 35,409 24.5 12,079 8.3 144,848 100 123