Table 4.
Multivariate adjusted* case-control odds ratios and 95% confidence intervals for all breast cancer cases, triple-negative and non triple-negative cases in relation to OC risk factors, stratified by age at diagnosis ≤40 and 41-45 years, 1983-1992.
| Triple–negative status | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Controls (N=1,569) |
All breast cancer (N=897) | Triple-negative (N=187) | Non triple-negative (N=710) | ||||||||
| n (%) | n (%) | OR | (95% CI) | n (%) | OR | (95% CI) | n (%) | OR | (95% CI) | P Value† | |
| Among women ≤ 40 years of age | |||||||||||
| Oral contraceptive use | n=1156 | n=590 | n=141 | n=449 | |||||||
| OC use (yrs) | |||||||||||
| Never/<1 | 299 (25.9) | 121 (20.5) | 1.0 | Reference | 11 (7.8) | 1.0 | Reference | 110 (24.5) | 1.0 | Reference | |
| 1+ | 857 (74.1) | 469 (79.5) | 1.6 | (1.1-2.1) | 130 (92.2) | 4.2 | (1.9-9.3) | 339 (75.5) | 1.2 | (0.9-1.7) | <.001 |
| OC duration (yrs)‡ | |||||||||||
| 1-<3 | 242 (20.9) | 126 (21.4) | 1.5 | (1.0-2.2) | 31 (22.0) | 3.0 | (1.2-7.3) | 95 (21.2) | 1.3 | (0.9-2.0) | |
| 3-<6 | 261 (22.6) | 141 (23.9) | 1.6 | (1.1-2.4) | 39 (27.7) | 4.9 | (2.1-11.6) | 102 (22.7) | 1.2 | (0.8-1.9) | |
| 6+ | 354 (30.6) | 202 (34.2) | 1.5 | (1.1-2.2) | 60 (42.6) | 4.7 | (2.0-10.8) | 142 (31.6) | 1.2 | (0.8-1.7) | |
| P for trend | .86 | .17 | .58 | .10 | |||||||
| Age at first use (yrs)‡ | |||||||||||
| 22+ | 166 (14.4) | 79 (13.4) | 1.3 | (0.8-2.1) | 20 (14.2) | 3.5 | (1.4-9.1) | 59 (13.1) | 1.1 | (0.7-1.8) | |
| 18-<22 | 499 (43.2) | 270 (45.8) | 1.4 | (1.0-2.0) | 75 (53.2) | 3.7 | (1.7-8.5) | 195 (43.4) | 1.1 | (0.8-1.6) | |
| <18 | 192 (16.6) | 120 (20.3) | 2.3 | (1.5-3.5) | 35 (24.8) | 6.4 | (2.6-15.6) | 85 (18.9) | 1.8 | (1.2-2.8) | |
| P for trend | .02 | .12 | .04 | .93 | |||||||
| Years since first use‡ | |||||||||||
| <20 | 721 (62.4) | 368 (62.4) | 1.5 | (1.1-2.1) | 108 (76.6) | 4.2 | (1.9-9.5) | 260 (57.9) | 1.2 | (0.8-1.7) | |
| 20+ | 136 (11.8) | 101 (17.1) | 1.8 | (1.2-2.9) | 22 (15.6) | 4.2 | (1.6-10.8) | 79 (17.6) | 1.6 | (1.0-2.5) | .45 |
| Years since last use‡ | |||||||||||
| Current | 117 (10.1) | 43 (7.3) | 1.2 | (0.6-2.1) | 16 (11.3) | 4.5 | (1.6-13.1) | 27 (6.0) | 0.8 | (0.4-1.5) | |
| 1-<10 | 388 (33.6) | 210 (35.6) | 1.7 | (1.2-2.4) | 62 (44.0) | 5.1 | (2.2-11.6) | 148 (33.0) | 1.3 | (0.9-1.9) | |
| 10-<15 | 240 (20.8) | 148 (25.1) | 1.7 | (1.1-2.4) | 41 (29.1) | 4.2 | (1.7-9.9) | 107 (23.8) | 1.4 | (0.9-2.1) | |
| 15+ | 112 (9.7) | 68 (11.5) | 1.3 | (0.8-2.1) | 11 (7.8) | 2.1 | (0.7-6.2) | 57 (12.7) | 1.2 | (0.7-2.0) | |
| P for trend | .95 | .15 | .46 | .07 | |||||||
| Among women 41-45years of age | |||||||||||
| Oral contraceptive use | n=413 | n=307 | n=46 | n=261 | |||||||
| OC use (yrs) | |||||||||||
| Never/<1 | 108 (26.2) | 76 (24.8) | 1.0 | Reference | 11 (23.9) | 1.0 | Reference | 65 (25.0) | 1.0 | Reference | |
| 1+ | 305 (73.8) | 230 (75.2) | 1.0 | (0.7-1.5) | 35 (76.1) | 0.9 | (0.4-2.2) | 195 (75.0) | 1.0 | (0.7-1.6) | .93 |
| OC duration (yrs)‡ | |||||||||||
| 1-<3 | 85 (20.6) | 58 (19.0) | 0.9 | (0.5-1.6) | 4 (8.7) | 0.4 | (0.1-1.6) | 54 (20.8) | 1.0 | (0.6-1.8) | |
| 3-<6 | 96 (23.2) | 79 (25.8) | 1.2 | (0.7-2.0) | 12 (26.1) | 1.1 | (0.4-3.0) | 67 (25.8) | 1.2 | (0.7-2.1) | |
| 6+ | 124 (30.0) | 93 (30.4) | 0.9 | (0.6-1.6) | 19 (41.3) | 1.3 | (0.5-3.3) | 74 (28.5) | 0.9 | (0.5-1.5) | |
| P for trend | .91 | .11 | .65 | .06 | |||||||
| Age at first use (yrs)‡ | |||||||||||
| 22+ | 94 (22.8) | 80 (26.1) | 1.0 | (0.6-1.8) | 11 (23.9) | 0.8 | (0.3-2.5) | 69 (26.5) | 1.1 | (0.6-1.9) | |
| 18-<22 | 175 (42.4) | 120 (39.2) | 1.0 | (0.6-1.6) | 17 (37.0) | 0.9 | (0.4-2.3) | 103 (39.6) | 1.0 | (0.6-1.6) | |
| <18 | 36 (8.7) | 30 (9.8) | 1.1 | (0.6-2.3) | 7 (15.2) | 1.3 | (0.4-4.9) | 23 (8.8) | 1.1 | (0.5-2.3) | |
| P for trend | .85 | .57 | 1.0 | .59 | |||||||
| Years since first use‡ | |||||||||||
| <20 | 54 (13.1) | 41 (13.4) | 1.0 | (0.5-1.9) | 6 (13.0) | 1.0 | (0.3-3.6) | 35 (13.5) | 1.0 | (0.5-1.9) | |
| 20+ | 251 (60.8) | 189 (61.8) | 1.0 | (0.7-1.6) | 29 (63.0) | 0.9 | (0.4-2.2) | 160 (61.5) | 1.0 | (0.7-1.6) | .77 |
| Years since last use‡ | |||||||||||
| Current | 3 (0.7) | 0 (0.0) | 0.0 | N/A | 0 (0.0) | 0.0 | N/A | 0 (0.0) | 0.0 | N/A | |
| 1-<10 | 57 (13.8) | 42 (13.7) | 1.0 | (0.5-1.9) | 10 (21.7) | 1.8 | (0.6-5.4) | 32 (12.3) | 0.8 | (0.4-1.6) | |
| 10-<15 | 99 (24.0) | 65 (21.2) | 0.8 | (0.5-1.5) | 14 (30.4) | 1.0 | (0.4-2.8) | 51 (19.6) | 0.8 | (0.5-1.5) | |
| 15+ | 146 (35.4) | 123 (40.2) | 1.1 | (0.7-1.8) | 11 (23.9) | 0.7 | (0.2-1.8) | 112 (43.1) | 1.2 | (0.8-2.0) | |
| P for trend | .33 | .08 | .10 | .01 | |||||||
*
Risk factors adjusted for age, family history of breast cancer, and breastfeeding history
†
Pheterogeneity (association of risk factor with triple-negative vs. non triple-negative breast cancer)
‡
Ptrend and Pheterogeneity among OC users >1 year only