Table 3.

Association between selected breast cancer risk or protective factors and breast cancer subtypes among 804 cases and 2,502 controls participating in the Polish Breast Cancer Study

Subject characteristicsLuminal A (n = 552)
Luminal B (n = 48)
HER2-expressing (n = 61)
Basal-like (n = 95)
Unclassified (n = 48)
OR* (95% CI)OR* (95% CI)POR* (95% CI)POR* (95% CI)POR* (95% CI)P
Age at menarche (per 2 y increase)0.90 (0.95-1.08)0.98 (0.75-1.28)0.991.14 (0.86-1.50)0.260.78 (0.68-0.89)0.00090.92 (0.72-1.18)0.61
Number of full-term births
    10.50 (0.24-1.06)0.91 (0.09-8.83)0.871.50 (0.19-11.77)0.312.36 (0.43-13.01)0.140.57 (0.06-5.83)0.72
    ≥20.42 (0.21-0.84)0.56 (0.07-4.56)0.941.15 (0.17-7.63)0.291.80 (0.37-8.85)0.200.71 (0.09-5.71)0.44
Age at first full-term birth (per 5-y increase)1.08 (0.95-1.23)1.04 (0.70-1.55)0.950.87 (0.60-1.05)0.270.95 (0.71-1.27)0.471.06 (0.71-1.58)0.71
Age at menopause (per 5-y increase)1.13 (1.01-1.28)1.10 (0.78-1.57)0.931.09 (0.81-1.46)0.821.02 (0.82-1.28)0.381.46 (0.99-2.15)0.19
BMI in premenopausal women (per five units)0.71 (0.57-0.88)0.88 (0.48-1.60)0.370.53 (0.25-1.12)0.381.18 (0.86-1.64)0.0031.17 (0.68-2.00)0.12
BMI in postmenopausal women (per five units)1.00 (0.90-1.12)1.02 (0.74-1.42)0.910.97 (0.73-1.28)0.990.87 (0.66-1.14)0.371.08 (0.78-1.48)0.85
Family history§1.72 (1.21-2.45)2.31 (0.88-6.08)0.612.35 (1.03-5.38)0.573.17 (1.69-5.92)0.110.94 (0.28-3.16)0.49
  • NOTE: Molecular subtypes were defined as luminal A (ER+ and/or PR+, HER2−), luminal B (ER+ and/or PR+, HER2+), HER2 (HER2+, ER−, PR−), basal-like (ER−, PR−, HER2−, CK5+, and/or HER1+), and unclassified or normal-like (negative for all five markers; ref. 4).

  • * ORs and 95% CI were obtained from case-control comparisons using polytomous logistic regression analyses adjusting for age, study site, education level, menopausal status, oral HRT use among postmenopausal women, previous benign breast disease, mammogram screening, and all factors shown in the table.

  • P values were obtained from comparisons of each tumor subtype to luminal A group using unconditional logistic regression analysis adjusting for all risk factors mentioned in the first footnote.

  • Compared with nulliparous women.

  • § Family history of breast cancer among first-degree relatives; compared with no family history.