Breast cancer risk in male twins: joint analyses of four twin cohorts in Denmark, Finland, Sweden and the United States.
To test the hypothesis that in utero exposure to high levels of oestrogen increases the risk of male breast cancer, we followed 115 235 male twins for more than 3.5 million person-years at risk. We observed 11 cases of male breast cancer versus 16.16 expected based on national rates (standardized rate ratio 0.68, 95% confidence interval 0.34-1.22) and conclude that any adverse influence of in utero oestrogen exposure is likely to be small.
Whiteman
D C
DC
ICRF General Practice Research Group, University of Oxford, Oxford, UK.
Murphy
M F
MF
Verkasalo
P K
PK
Page
W F
WF
Floderus
B
B
Skytthe
A
A
Holm
N V
NV
D018567:Breast Neoplasms, Male / Q000209:etiology*; D015331:Cohort Studies; D003718:Denmark; D004200:Diseases in Twins / Q000209:etiology*; D004967:Estrogens / Q000009:adverse effects; D005260:Female; D005387:Finland; D006801:Humans; D008297:Male; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D012307:Risk Factors; D013548:Sweden; D014427:Twins / Q000706:statistics & numerical data; D014429:Twins, Dizygotic / Q000706:statistics & numerical data; D014430:Twins, Monozygotic / Q000706:statistics & numerical data; D014481:United States
D004967:Estrogens