From: Incidence of breast cancer in Chinese women exposed to the 1959–1961 great Chinese famine
Birth year | p value | |||
---|---|---|---|---|
1955–1958 (N = 25,836) | 1959–1962 (N = 17,772) | 1963–1966 (N = 15,452) | ||
Participant rates (%) | 68.7 | 61.2 | 54.6 | |
Age (Mean ± SD) | 52.7 ± 1.9 | 49.1 ± 1.9 | 45.2 ± 1.8 | <0.0001 |
Educational level (N, %) | ||||
Primary school or below | 5448 (21.1) | 2307 (13.0) | 1521 (9.8) | |
Junior high School | 11,926 (46.2) | 8669 (48.8) | 9466 (61.3) | |
Senior high school | 637 (2.5) | 511 (2.9) | 3336 (21.6) | |
Technical school | 7334 (28.4) | 5905 (33.2) | 693 (4.5) | |
College or above | 491 (1.9) | 380 (2.1) | 436 (2.8) | <0.0001 |
Marriage status (N, %) | ||||
Single | 80 (0.3) | 52 (0.3) | 32 (0.2) | |
Married | 25,070 (97.0) | 17,279 (97.2) | 15,052 (97.4) | |
Remarried | 351 (1.4) | 243 (1.4) | 226 (1.5) | |
Separate/divorced | 163 (0.6) | 119 (0.7) | 111 (0.7) | |
Widow | 172 (0.7) | 79 (0.4) | 31 (0.2) | 0.0005 |
Age at menarche <12 years (N, %) | 66 (0.3) | 50 (0.3) | 46 (0.3) | 0.41 |
Irregular cycle (N, %) | 7040 (27.3) | 3374 (19.0) | 2488 (16.1) | <0.0001 |
Age at menopause ≥55 years (N, %) | 96 (0.37) | 32 (0.18) | 12 (0.08) | <0.0001 |
Infertility (N, %) | 446 (1.7) | 282 (1.6) | 241 (1.6) | 0.17 |
Age at first birth >35 years (N, %) | 122 (0.5) | 90 (0.5) | 42 (0.5) | 0.86 |
Breastfeeding (N, %) | 19,311 (74.7) | 14,780 (83.2) | 13,241 (85.7) | <0.0001 |
Estrogen use (N, %) | 405 (1.6) | 219 (1.2) | 223 (1.4) | 0.16 |
Family history of breast cancer (N, %) | 297 (1.2) | 136 (0.8) | 101 (0.7) | <0.0001 |