Table 2. Reproductive factors and risk of oesophageal and gastric junction adenocarcinoma in Irish, United Kingdom (UK), United States (US) and Australian studies, expressed as odds ratios (ORs) with 95% confidence intervals (CIs).
| Variables | Controls (n = 862) Number (%)a | Cases (n = 218) Number (%)a | Minimally adjusted ORs (95% CI) b | Adjusted ORs c (95% CI) |
|---|---|---|---|---|
| Age at first menstruation (years)g | ||||
| ≤13 | 473 (60) | 86 (60) | 1.00 | 1.00 |
| >13 | 313 (40) | 56 (39) | 0.89 (0.39–2.04) | 1.01 (0.35–2.91) |
| Missing | 2 (<1) | 2 (1.4) | – | – |
| Age when periods ended (years)h | ||||
| 50–70 | 178 (31) | 39 (33) | 1.00 | 1.00 |
| <50 | 217 (37) | 58 (49) | 1.15 (0.72–1.86) | 1.06 (0.64–1.77) |
| Not stopped | 39 (7) | 5 (4) | 0.64 (0.18–2.30) | 0.65 (0.17–2.50) |
| Missing | 146 (25) | 16 (14) | – | – |
| Ever pregnantf | ||||
| No | 74 (11) | 22 (11) | 1.00 | 1.00 |
| Yes | 578 (88) | 166 (86) | 0.91 (0.52–1.60) | 1.02 (0.55–1.87) |
| Missing | 2 (<1) | 4 (2) | – | – |
| Number of childrene | ||||
| 3+ (ref) | 368 (43) | 90 (41) | 1.00 | 1.00 |
| 1–2 | 334 (39) | 90 (41) | 1.18 (0.82–1.69) | 1.20 (0.84–1.72) |
| 0 | 158 (18) | 34 (16) | 1.03 (0.64–1.68) | 1.27 (0.77–2.10) |
| Missing | 2 (0.2) | 4 (2) | – | – |
| Breastfeeding among women who had a live birthf,d | ||||
| Had children; never breastfed | 101 (16) | 52 (27) | 1.00 | 1.00 |
| Had children; ever breastfed | 450 (69) | 102 (53) | 0.52 (0.33–0.80) | 0.58 (0.37–0.92) |
| Unknown | 14 (2) | 11 (6) | – | – |
| Missing | 89 (14) | 27 (14) | – | – |
| Children and Breastfeeding Durationf | ||||
| Had children; never breastfed | 101 (15) | 52 (27) | 1.00 | 1.00 |
| Breastfed ≤6 months | 137 (21) | 46 (24) | 0.62 (0.37–1.04) | 0.63 (0.37–1.08) |
| Breastfed 7–12 months | 120 (18) | 27 (14) | 0.55 (0.31–0.98) | 0.65 (0.35–1.18) |
| Breastfed > 12 months | 189 (29) | 26 (14) | 0.34 (0.19–0.61) | 0.42 (0.23–0.77) |
| Unknown | 18 (3) | 14 (7) | – | – |
| Missing | 89 (14) | 27 (14) | – | – |
| Use of hormone replacement therapy among women aged >50 yearsh | ||||
| Never | 218 (52) | 64 (61) | 1.00 | 1.00 |
| Ever | 193 (46) | 35 (33) | 0.76 (0.47–1.23) | 0.75 (0.45–1.24) |
| Missing | 5 (1) | 6 (6) | – | – |
| Use of oral contraceptivesg | ||||
| No | 373 (47) | 78 (54) | 1.00 | 1.00 |
| Yes | 411 (52) | 60 (42) | 1.00 (0.61–1.63) | 0.92 (0.55–1.54) |
| Missing | 4 (0.5) | 6 (4) | – | – |
a
Persons with inapplicable or missing data in any covariate included in the models were excluded.
b
Minimally adjusted odds ratios adjusted for age and study.
c
Models adjusted for age, reflux symptoms (GOR and/or heartburn), years of education, smoking status, alcohol, BMI and study.
d
Models for breastfeeding among parous women also adjusted for number of children.
e
Models included data from Irish, UK, US and Australian studies.
f
Models included data from Irish, UK and Australian studies (n = 846).
g
Models included data from Irish, US and Australian studies (n = 932).
h
Models included data from Irish and Australian studies (n = 698).