Table 4.

ORs and 95% CIs for an association between vitamin D–related exposure variables at ages 45 to 54 (sun exposure and dietary vitamin D) and breast cancer in cases and controls

Cases (%)Controls (%)OR* (95% CI)OR (95% CI)
Days outside per week
    <3120 (16)93 (11)1.45 (1.07-1.97)1.29 (0.94-1.76)
    3-4123 (16)137 (16)1.01 (0.77-1.34)1.00 (0.75-1.33)
    5-6115 (15)145 (17)0.89 (0.68-1.18)0.86 (0.65-1.15)
    7414 (53)462 (56)1.001.00
    P for trend0.27
Outdoor activity episodes§
    <27082 (11)86 (11)1.001.00
    270-599141 (18)149 (20)1.00 (0.68-1.46)1.01 (0.68-1.50)
    600-1,076213 (33)268 (30)0.83 (0.58-1.18)0.80 (0.55-1.15)
    1,077+271 (38)309 (38)0.91 (0.64-1.28)0.91 (0.64-1.31)
    P for trend0.59
Outdoor job
    Never728 (91)795 (90)1.001.00
    1 y15 (2)20 (2)0.82 (0.41-1.64)0.82 (0.41-1.64)
    ≥1 y60 (7)74 (8)0.89 (0.62-1.28)0.89 (0.62-1.28)
    P for trend0.47
Limbs covered
    No441 (57)507 (60)1.001.00
    Partial184 (24)191 (23)1.11 (0.87-1.41)1.13 (0.88-1.45)
    Yes152 (20)144 (17)1.23 (0.95-1.60)1.22 (0.93-1.60)
    P for trend0.13
Skin burned/darkened
    No102 (13)93 (11)1.22 (0.90-1.64)1.24 (0.91-1.68)
    Yes678 (87)749 (89)1.001.00
Sunscreen use
    Yes377 (47)411 (55)0.73 (0.60-0.89)0.78 (0.64-0.96)
    No466 (53)368 (45)1.001.00
Sun trip in winter
    No432 (52)376 (49)1.001.00
    Yes402 (48)411 (51)0.89 (0.73-1.08)0.93 (0.76-1.13)
Sunlamp use
    No681 (85)733 (82)1.001.00
    Yes122 (15)156 (18)0.88 (0.67-1.14)0.84 (0.64-1.11)
Cod liver oil use
    No770 (97)845 (96)1.001.00
    Yes23 (3)37 (4)0.70 (0.41-1.19)0.69 (0.40-1.19)
Milk (glasses/wk)
    None152 (19)153 (18)1.001.00
    <5186 (24)188 (22)1.00 (0.74-1.35)0.95 (0.69-1.30)
    5-9215 (27)249 (29)0.87 (0.65-1.16)0.85 (0.63-1.15)
    ≥10230 (29)264 (31)0.87 (0.66-1.16)0.90 (0.67-1.21)
    P for trend0.42
Intake of salmon or tuna per week
    None69 (9)69 (8)1.001.00
    <1228 (29)244 (28)0.94 (0.64-1.37)0.98 (0.66-1.45)
    1228 (29)291 (34)0.77 (0.53-1.13)0.84 (0.57-1.24)
    >1258 (33)250 (29)1.02 (0.70-1.48)1.19 (0.81-1.77)
    P for trend0.20
Supplement use
    Vitamin D76 (9)99 (11)0.82 (0.58-1.16)0.84 (0.59-1.19)
    Multivitamins347 (43)376 (42)0.99 (0.79-1.24)0.99 (0.79-1.25)
    Other vitamin supplements124 (15)144 (16)0.92 (0.68-1.23)0.86 (0.63-1.17)
    None256 (32)270 (30)1.001.00
  • * ORs with 95% CIs adjusted for reference age.

  • ORs with 95% CIs adjusted for reference age, ethnicity, family history in first-degree relatives, ever breast-fed, education, age menarche, and age at first birth.

  • Number of days outside for at least half an hour during the summer (June, July, and August).

  • § Number of outdoor activity episodes derived from reported outdoor activities done for at least 30 min between 9 a.m. and 5 p.m. at least once per month during June, July, and August along with frequency (days per week or month) and duration (number of years).