Table 3.
Relative risk of breast cancer in relation to participant’s age at death of parent, Breakthrough Generations Study
| Oestrogen receptor status of breast cancer | ||||||
|---|---|---|---|---|---|---|
| All cases | Positive | Negative | ||||
| Factor | No. of cases | Adjusted RR (95% CI)(a) | No. of Cases | Adjusted RR (95% CI)(a) | No. of cases | Adjusted RR (95% CI)(a) |
| All mothers | ||||||
| Mother deceased | ||||||
| No | 916 | 1.00 | 700 | 1.00 | 146 | 1.00 |
| Yes | 867 | 0.99 (0.89-1.10) | 690 | 1.00 (0.89-1.13) | 121 | 0.96 (0.72-1.27) |
| Age of participant at mother’s death, years | ||||||
| <20 | 75 | 1.31 (1.02-1.67) | 55 | 1.21 (0.89-1.61) | 13 | 1.67 (0.93-2.98) |
| 20-29 | 91 | 1.02 (0.82-1.27) | 72 | 1.04 (0.81-1.33) | 13 | 1.01 (0.57-1.80) |
| 30-39 | 178 | 1.07 (0.91-1.27) | 135 | 1.04 (0.86-1.26) | 26 | 1.09 (0.71-1.68) |
| 40-49 | 221 | 0.88 (0.75-1.03) | 187 | 0.95 (0.80-1.13) | 23 | 0.62 (0.39-0.99) |
| ≥50 | 302 | 0.94 (0.81-1.10) | 241 | 0.96 (0.81-1.14) | 46 | 1.01 (0.68-1.49) |
| P trend=0.059 | P trend=0.22 | P trend=0.46 | ||||
| Mothers who did not have breast or ovarian cancer | ||||||
| Mother deceased | ||||||
| No | 790 | 1.00 | 603 | 1.00 | 128 | 1.00 |
| Yes | 633 | 0.94 (0.83-1.07) | 507 | 0.98 (0.85-1.13) | 88 | 0.82 (0.60-1.13) |
| Age of participant at mother’s death, years | ||||||
| <20 | 41 | 1.17 (0.85-1.61) | 29 | 1.05 (0.72-1.55) | 7 | 1.35 (0.62-2.92) |
| 20-29 | 54 | 1.04 (0.78-1.38) | 43 | 1.07 (0.78-1.47) | 7 | 0.86 (0.40-1.86) |
| 30-39 | 119 | 1.05 (0.86-1.29) | 92 | 1.05 (0.84-1.32) | 16 | 0.92 (0.54-1.57) |
| 40-49 | 173 | 0.86 (0.72-1.03) | 150 | 0.98 (0.80-1.19) | 16 | 0.50 (0.28-0.87) |
| ≥50 | 246 | 0.89 (0.75-1.05) | 193 | 0.90 (0.75-1.09) | 42 | 0.98 (0.65-1.49) |
| P trend=0.046 | P trend=0.19 | P trend=0.86 | ||||
| All fathers | ||||||
| Father deceased | ||||||
| No | 730 | 1.00 | 568 | 1.00 | 104 | 1.00 |
| Yes | 1053 | 0.95 (0.85-1.06) | 822 | 0.92 (0.81-1.04) | 163 | 1.23 (0.92-1.65) |
| Age of participant at father’s death, years | ||||||
| <20 | 105 | 0.94 (0.76-1.16) | 80 | 0.88 (0.69-1.12) | 18 | 1.37 (0.82-2.30) |
| 20-29 | 163 | 0.96 (0.81-1.15) | 133 | 0.98 (0.80-1.19) | 22 | 1.12 (0.69-1.80) |
| 30-39 | 259 | 0.92 (0.79-1.06) | 205 | 0.90 (0.76-1.07) | 37 | 1.08 (0.72-1.61) |
| 40-49 | 326 | 1.00 (0.87-1.16) | 257 | 0.98 (0.83-1.15) | 49 | 1.30 (0.89-1.90) |
| ≥50 | 200 | 0.91 (0.77-1.09) | 147 | 0.82 (0.67-1.00) | 37 | 1.50 (0.97-2.31) |
| P trend=0.97 | P trend=0.56 | P trend=0.40 | ||||
RR relative risk, CI confidence interval
(a) Analyses adjusted for attained age, age at menarche, age at first birth and parity, cumulative duration of breast feeding, oral contraceptive use, postmenopausal hormone use, benign breast disease, BMI at age 20, postmenopausal BMI and time-updated menopausal status, height, physical activity, alcohol consumption, cigarette smoking, family history of breast cancer and socioeconomic status