Table 1 Characteristics of the study cohorts
Patient cohort (year of primary diagnosis) | Female population* | Number of breast cancers diagnosed per year** | Number of breast cancers in the cohort (n, %)** | Age at diagnosis (median, range) | Proportion of axillary lymph node negative cancers | Proportion of estrogen receptor-positive cancers | Proportion of progesterone receptor-positive cancers |
|---|---|---|---|---|---|---|---|
1982 to 1986 | |||||||
population-based** | 215,639 | 191 | 957 | 63 (27 to 92) | 53.1% | NA | NA |
studied cohort | 310 (32.4%) | 59 (30 to 88) | 56.6% | 59.4% | 69.7% | ||
1989 to 1992 | |||||||
population-based**,*** | 220,257 | 246 | 985 | 60 (28 to 92) | 58.9% | 72.0% | 63.0% |
studied cohort | 108 (11.0%) | 64 (34 to 88) | 65.2% | 77.9% | 55.9% | ||
2004 to 2005 | |||||||
population-based** | 231,000 | 389 | 777 | NA | NA | NA | NA |
studied cohort | 713 (91.8%) | 60 (25 to 94) | 56.3% | 89.8%**** | 77.3% |