Table 3 Combination oral contraceptive use and breast cancer risk

From: Hormonal content and potency of oral contraceptives and breast cancer risk among young women

 

<35 years

35–44 years

Total (<45 years)

 

Cases ( N =267)

Controls ( N =289)

RR

95% CI

Cases ( N =1373)

Controls ( N =1203)

RR

95% CI

Cases ( N =1640)

Controls ( N =1492)

RR

95% CI

Non users/<6 months of use

58

96

1.00

 

313

310

1.00

 

371

406

1.00

 

Ever-users

209

193

2.05

1.3–3.2

1060

893

1.12

0.9–1.4

1269

1086

1.24

1.0–1.5

Recency of OC use (relevant to diagnosis/interview)

            

 Within 5 years

135

123

2.22

1.4–3.5

174

135

1.30

1.0–1.8

309

258

1.47

1.2–1.9

 6–10 years ago

43

39

2.03

1.1–3.7

163

134

1.17

0.9–1.6

206

173

1.33

1.0–1.7

 >10 years ago

31

31

1.52

0.8–3.0

723

624

1.07

0.9–1.3

754

655

1.13

0.9–1.4

Content of pill preparation

            

 Known

190

184

1.96

1.3–3.0

845

738

1.08

0.9–1.3

1035

922

1.19

1.0–1.4

 Unknown

19

9

3.97

1.5–10.6

215

155

1.33

1.0–1.8

234

164

1.50

1.1–1.9

  1. Note: RRs and 95% CIs were estimated using maximum likelihood methods and adjusting for age, site, race, menopausal status, a combination variable for age at first birth and number of births, age at menarche, family history of breast cancer, body mass index, and mammography use.
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