Table 2.
Association of significant reproductive factors and lung cancer risk, stratified by subgroups (highest vs. lowest category)
| Reproductive factorsa | n | OR (95% CI)b | Case-Control | Cohort | ||
|---|---|---|---|---|---|---|
| n | OR (95% CI)b | n | OR (95% CI)b | |||
| Parity (highest vs. lowest) | ||||||
| Overall lung cancer | 24 | 0.83 (0.72, 0.96) | 15 | 0.82 (0.68, 0.98) | 9 | 0.85 (0.68, 1.05) |
| Asian | 12 | 0.70 (0.58, 0.86) | 7 | 0.81 (0.65, 1.01) | 5 | 0.58 (0.44, 0.75) |
| Caucasian | 8 | 1.03 (0.85, 1.25) | 5 | 0.93 (0.60, 1.43) | 3 | 1.12 (0.96, 1.31) |
| Adenocarcinoma | 10 | 0.83 (0.63, 1.09) | 5 | 1.00 (0.82, 1.22) | 5 | 0.71 (0.43, 1.16) |
| Asian | 5 | 0.72 (0.37, 1.39) | 2 | 1.22 (0.86, 1.73) | 3 | 0.45 (0.28, 0.71) |
| Caucasian | 4 | 0.93 (0.76, 1.13) | 2 | 0.74 (0.44, 1.24) | 2 | 0.97 (0.78, 1.20) |
| Non-small cell lung cancer | 10 | 0.84 (0.63, 1.11) | 5 | 0.81 (0.51, 1.29) | 5 | 0.85 (0.57, 1.27) |
| Asian | 4 | 0.82 (0.33, 2.07) | 2 | 1.22 (0.86, 1.73) | 2 | 0.39 (0.18, 0.84) |
| Caucasian | 4 | 0.94 (0.69, 1.29) | 2 | 0.74 (0.44, 1.24) | 2 | 0.97 (0.78, 1.20) |
| Never Smokers | 11 | 0.71 (0.54, 0.93) | 5 | 0.65 (0.52, 0.81) | 6 | 0.80 (0.51, 1.28) |
| Asian | 7 | 0.65 (0.54, 0.78) | ||||
| Caucasian | 2 | 0.99 (0.25, 3.85) | ||||
| Ever Smokers | 8 | 0.78 (0.59, 1.04) | 4 | 0.56 (0.41, 0.75) | 4 | 1.01 (0.76, 1.34) |
| Asian | 4 | 0.54 (0.40, 0.75) | ||||
| Caucasian | 2 | 1.14 (0.92, 1.40) | ||||
| Parity (highest vs. nulliparous) | ||||||
| Overall lung cancer | 16 | 0.77 (0.62, 0.95) | 10 | 0.79 (0.62, 1.00) | 6 | 0.72 (0.49,1.06) |
| Asian | 5 | 0.56 (0.47, 0.67) | 1 | 0.61 (0.43, 0.87) | 4 | 0.55 (0.45, 0.66) |
| Caucasian | 8 | 0.96 (0.73, 1.26) | 6 | 0.83 (0.58, 1.18) | 2 | 1.22 (0.97, 1.52) |
| Adenocarcinoma | 8 | 0.71 (0.49, 1.01) | 4 | 0.83 (0.64, 1.08) | 4 | 0.66 (0.31, 1.41) |
| Asian | 3 | 0.45 (0.28, 0.71) | 3 | 0.45 (0.28, 0.71) | ||
| Caucasian | 4 | 0.84 (0.52, 1.35) | 3 | 0.66 (0.45, 0.98) | 1 | 1.41 (0.90, 2.20) |
| Age at first birth | ||||||
| Overall lung cancer | 19 | 0.85 (0.74, 0.98) | 12 | 0.77 (0.61, 0.97) | 7 | 0.94 (0.81, 1.08) |
| Asian | 9 | 0.90 (0.66, 1.22) | ||||
| Caucasian | 6 | 0.75 (0.65, 0.88) | ||||
| Adenocarcinoma | 10 | 0.84 (0.74, 0.95) | 6 | 0.85 (0.72, 1.00) | 4 | 0.82 (0.67, 1.01) |
| Asian | 3 | 0.62 (0.47, 0.83) | ||||
| Caucasian | 5 | 0.82 (0.68, 0.97) | ||||
| Non-natural menopause | ||||||
| Overall lung cancer | 11 | 1.52 (1.25, 1.86) | 6 | 1.83 (1.50, 2.22) | 5 | 1.17 (1.00, 1.37) |
| Asian | 4 | 1.36 (1.07, 1.72) | ||||
| Caucasian | 5 | 1.67 (1.12, 2.49) | ||||
| Adenocarcinoma | 6 | 1.41 (1.18, 1.69) | 5 | 1.64 (1.25, 2.14) | 1 | 1.24 (0.97, 1.59) |
| Caucasian | 5 | 1.44 (1.19, 1.74) | ||||
| Menstrual cycle length | ||||||
| Overall lung cancer | 7 | 0.79 (0.65, 0.96) | 7 | 0.79 (0.65, 0.96) | ||
| Asian | 3 | 0.64 (0.49, 0.85) | ||||
| Caucasian | 4 | 0.98 (0.74, 1.28) | ||||
| Adenocarcinoma | 4 | 0.79 (0.55, 1.14) | 4 | 0.79 (0.55, 1.14) | ||
| Caucasian | 3 | 0.79 (0.51, 1.21) | ||||
aSubgroup analyses were conducted if there were at least four studies published for that reproductive variable
bAdjusted odds ratio (OR) and 95% confidence interval (CI). Highest non-reference category as compared to the lowest reference group