Table 3.
Estimates for mean ages at diagnosis of patients with early- or late-onset breast cancer from two-component mixture models*
| Mean age, y (95% CI) |
Probability†, % (95% CI) | AIC |
||||
| Calendar period | Race | Early-onset group | Late-onset group | Mixture | Single density | |
| 1975–1979 | White | 47.9 (34.6 to 61.2) | 83.4 (70.1 to 96.7) | 77.0 (73.0 to 80.9) | −177 052 | −177 060 |
| Black | 42.4 (−41.9 to 126.7) | 69.8 (−14.5 to 154.1) | 43.0 (15.6 to 70.4) | −12 706 | −12 716 | |
| 1980–1984 | White | 52.1 (48.2 to 56.0) | 79.0 (75.1 to 82.9) | 69.0 (65.1 to 72.9) | −203 304 | −203 314 |
| Black | 32.0 (13.2 to 50.8) | 51.6 (32.8 to 70.4) | 17.0 (11.1 to 22.9) | −16 180 | −16 188 | |
| 1985–1989 | White | 39.2 (31.2 to 47.2) | 67.9 (59.9 to 75.9) | 25.0 (23.0 to 27.0) | −257 709 | −257 717 |
| Black | 36.3 (7.1 to 65.5) | 61.4 (32.2 to 90.6) | 15.9 (5.3 to 26.5) | −21 259 | −21 269 | |
| 1990–1994 | White | 46.8 (46.6 to 47.0) | 71.0 (70.8 to 71.2) | 33.0 (31.8 to 34.2) | −280 278 | −280 286 |
| Black | 39.1 (26.0 to 52.2) | 60.4 (47.3 to 73.5) | 20.0 (10.2 to 29.8) | −26 053 | −26 063 | |
| 1995–1999 | White | 46.2 (43.8 to 48.6) | 73.5 (71.1 to 75.6) | 48.0 (46.4 to 49.6) | −312 921 | −312 929 |
| Black | 46.7 (43.3 to 50.0) | 70.9 (67.6 to 74.2) | 56.3 (51.4 to 61.2) | −30 803 | −30 808 | |
| 2000–2004 | White | 46.8 (45.6 to 48.0) | 76.9 (75.7 to 78.1) | 64.0 (62.2 to 65.8) | −319 002 | −319 010 |
| Black | 50.2 (47.5 to 52.9) | 73.7 (71.0 to 76.4) | 68.7 (64.2 to 73.2) | −33 939 | −33 945 | |
*
AIC were used to determine model fit, with the larger values corresponding to the model with the best fit to the data. For white and black women, a mixture model (ie, more than one breast cancer population) fit the data better than a single cancer population (single density model). CI = confidence interval; AIC = Akaike information criteria.
†
Probability of being in the early-age-at-onset group at the time of initial breast cancer diagnosis.