Table 3. Risks of breast cancer after supradiaphragmatic radiotherapy in relation to pregnancy history.
| Risk factor | Cases | Controls | Total | ORa (95% CI) | P-value |
|---|---|---|---|---|---|
|
Any full-term pregnancies | |||||
| No | 46 | 365 | 411 | 1.00 | |
| Yes | 122 | 814 | 936 | 1.17 (0.79–1.73) | 0.42 |
| Unknown |
0 |
2 |
2 |
— |
— |
|
Full-term pregnancy before start of sRT | |||||
| No | 203 | 1516 | 1719 | 1.00 | |
| Yes | 57 | 717 | 774 | 0.77 (0.52–1.12) | 0.17 |
| Unknown |
0 |
4 |
4 |
— |
— |
|
Full-term pregnancy after start of sRT | |||||
| No | 74 | 637 | 711 | 1.00 | |
| Yes | 94 | 542 | 636 | 1.33 (0.92–1.92) | 0.13 |
| Unknown |
0 |
2 |
2 |
— |
— |
|
Timing of first FTP in relation to sRT | |||||
| No FTPs | 42 | 351 | 393 | 1.00 | |
| 1st FTP more than 10 years before sRT | 9 | 54 | 63 | 1.52 (0.59–3.88) | 0.38 |
| 1st FTP 5–10 years before sRT | 8 | 110 | 118 | 0.64 (0.27–1.55) | 0.32 |
| 1st FTP <5 years before sRT | 23 | 206 | 229 | 1.03 (0.57–1.84) | 0.93 |
| sRT during 1st FTP | 2 | 10 | 12 | 1.81 (0.35–9.33) | 0.48 |
| 1st FTP <5 years after sRT | 33 | 198 | 231 | 1.41 (0.83–2.38) | 0.20 |
| 1st FTP 5–10 years after sRT | 27 | 142 | 169 | 1.39 (0.79–2.44) | 0.26 |
| 1st FTP >10 years after sRT | 17 | 70 | 87 | 1.25 (0.63–2.49) | 0.52 |
| Unknown | 7 | 40 | 47 | 1.03 (0.40–2.63) | 0.95 |
Abbreviations: CI=confidence interval; FTP=full-term pregnancy; OR=odds ratio; sRT=supradiaphragmatic radiotherapy.
a
Odds ratios are adjusted for age and year of treatment, duration between treatment and questionnaire completion, calendar year of birth, sRT field, ovarian-toxic treatment.