Table 3.

Adjusted HRs and 95% CIs for incident breast cancer by region of residence at baseline (Southern vs Northern residence) and solar irradiance (low vs high solar exposure) stratified by breast cancer tumor characteristics: the WHIOS (n = 71,662)

CasesNorthern (>40°) vs Southern (≤37°)Langleys (gm-cal) per cm2 (300-325 vs 475-500)Watts (J/s) per m2 (0.4-0.5 vs 1.5-1.9)
ER status
    ER+1,9321.02 (0.92, 1.13)0.97 (0.86, 1.11)0.86 (0.73, 1.01)
    ER−3460.97 (0.76, 1.25)0.90 (0.65, 1.25)1.00 (0.69, 1.46)
PR status
    PR+1,6071.07 (0.95, 1.20)1.08 (0.94, 1.25)0.90 (0.75, 1.08)
    PR−6340.90 (0.75, 1.08)0.71 (0.56, 0.90)0.79 (0.61, 1.04)
ER/PR status
    ER+/PR+1,5721.07 (0.96, 1.21)1.09 (0.94, 1.26)0.90 (0.75, 1.08)
    ER+/PR−3220.83 (0.64, 1.07)0.59 (0.42, 0.82)0.64 (0.45, 0.93)
    ER−/PR+350.77 (0.36, 1.67)0.83 (0.30, 2.33)0.79 (0.25, 2.48)
    ER−/PR−3051.00 (0.77, 1.30)0.90 (0.63, 1.27)1.01 (0.68, 1.52)
Tumor size (cm)
    <0.51861.04 (0.73, 1.47)0.96 (0.60, 1.53)1.49 (0.84, 2.66)
    0.5-14751.20 (0.97, 1.49)1.02 (0.79, 1.33)0.96 (0.69, 1.33)
    >1 to 29820.90 (0.78, 1.05)0.88 (0.73, 1.05)0.75 (0.60, 0.93)
    >2 to 54971.09 (0.89, 1.35)1.03 (0.79, 1.35)0.98 (0.70, 1.35)
    >5860.49 (0.30, 0.79)0.45 (0.26, 0.80)0.49 (0.23, 1.03)
Lymph node involvement
    No1,8171.00 (0.89, 1.11)0.99 (0.87, 1.13)0.84 (0.71, 0.99)
    Yes6100.92 (0.79, 1.06)0.82 (0.65, 1.04)0.80 (0.60, 1.06)
Tumor grade
    Well-differentiated6310.93 (0.77, 1.12)0.74 (0.59, 0.92)0.53 (0.40, 0.70)
    Moderately differentiated9720.92 (0.79, 1.06)0.97 (0.81, 1.16)0.78 (0.62, 0.98)
    Poorly differentiated5671.15 (0.95, 1.41)1.23 (0.95, 1.60)1.30 (0.94, 1.80)
    Anaplastic641.50 (0.84, 2.68)1.06 (0.51, 2.22)1.46 (0.67, 3.17)
  • NOTE: Adjusted for age, race/ethnicity, education, weight, family history of breast cancer, age at menarche, age at menopause, parity, age at first birth, hormone therapy duration of use, alcohol intake, and physical activity.