Table 1.
Descriptive characteristics of the cohort comprising of women born after 1965 and diagnosed with primary invasive breast cancer between 2009 and 2016 in Scotland stratified by surrogate molecular subtypes
| Total number of cases (%): |
Luminal A-like | Luminal B-like (HER2−) | Luminal B-like (HER2+) | HER2-overexpressed | TNBC | Overall |
|---|---|---|---|---|---|---|
| 1650 (40.2) |
998 (24.3) |
629 (15.3) |
214 (5.2) |
617 (15.0) |
4108 (100.0) |
|
| Age at diagnosis (years) | N (%) |
N (%) |
N (%) |
N (%) |
N (%) |
N (%) |
| 20–35 |
122 (7.4) |
133 (13.3) |
105 (16.7) |
37 (17.3) |
119 (19.3) |
516 (12.5) |
| 36–40 |
283 (17.2) |
239 (23.9) |
152 (24.2) |
55 (25.7) |
149 (24.1) |
878 (21.3) |
| 41–45 |
719 (43.6) |
400 (40.1) |
248 (39.4) |
76 (35.5) |
223 (36.1) |
1666 (40.6) |
| 46–50 |
526 (31.9) |
226 (22.6) |
124 (19.7) |
46 (21.5) |
126 (20.4) |
1048 (25.5) |
| *P value for heterogeneity between subtypes using chi-square test: < 0.001 | ||||||
| Number of births | ||||||
| 0 |
504 (30.5) |
291 (29.2) |
189 (30.0) |
45 (21.0) |
150 (24.3) |
1179 (28.7) |
| 1 |
370 (22.4) |
215 (21.5) |
151 (24.0) |
53 (24.8) |
153 (24.8) |
942 (22.9) |
| 2 |
524 (31.8) |
337 (33.8) |
202 (32.1) |
77 (36.0) |
215 (34.8) |
1355 (33.0) |
| ≥ 3 |
252 (15.3) |
155 (15.5) |
87 (13.8) |
39 (18.2) |
99 (16.0) |
632 (15.4) |
| *P value for heterogeneity between subtypes using chi-square test: 0.111 | ||||||
| Number of parous cases (%): |
1146 (39.1) |
707 (24.1) |
440 (15.0) |
169 (5.8) |
467 (15.9) |
2929 (100.0) |
|---|---|---|---|---|---|---|
| N (%) |
N (%) |
N (%) |
N (%) |
N (%) |
N (%) |
|
| Age at first birth (years) | ||||||
| < 20 |
144 (12.5) |
89 (12.6) |
44 (10.0) |
18 (10.7) |
73 (15.6) |
368 (12.6) |
| 20–24 |
246 (21.5) |
162 (22.9) |
88 (20.0) |
43 (25.4) |
117 (25.1) |
656 (22.4) |
| 25–29 |
348 (30.4) |
195 (27.6) |
149 (33.9) |
49 (29.0) |
117 (25.1) |
858 (29.3) |
| 30–34 |
268 (23.4) |
169 (23.9) |
100 (22.7) |
45 (26.6) |
101 (21.6) |
683 (23.3) |
| ≥ 35 |
140 (12.2) |
92 (13.0) |
59 (13.4) |
14 (8.3) |
59 (12.6) |
364 (12.4) |
| *P value for heterogeneity between subtypes using chi-square test: 0.151 | ||||||
| Time since last birth (years)** | ||||||
| ≤ 2 |
76 (6.7) |
71 (10.1) |
53 (12.1) |
20 (11.9) |
70 (15.1) |
290 (10.0) |
| 3–5 |
120 (10.5) |
116 (16.5) |
70 (16.0) |
30 (17.9) |
73 (15.8) |
409 (14.1) |
| 6–10 |
279 (24.5) |
186 (26.5) |
115 (26.3) |
41 (24.4) |
121 (26.1) |
742 (25.5) |
| > 10 |
663 (58.3) |
329 (46.9) |
199 (45.5) |
77 (45.8) |
199 (43.0) |
1467 (50.4) |
*P value for heterogeneity between subtypes using chi-square test: < 0.001
*Significant at 5% level
**Total counts (N = 2908) exclude parous women that did not have a pregnancy before diagnosis of breast cancer