ASPO Abstracts
Associations of oral contraceptives with mammographic breast density
Category: Early Detection & Risk Prediction
Conference Year: 2020
Abstract Body:
Purpose: We investigated the associations of oral contraceptives (OC) use with percent breast density (PD),
absolute dense area (DA), non-dense area (NDA), and a novel image intensity variation (V) measure in
premenopausal women. Methods: This study included cancer-free women from a nested case-control study within
Nurses’ Health Study II cohort. Information on OC use was collected in 1989 and then updated biennially. OC use
was defined from the questionnaire closest to the mammogram date. PD, DA, and NDA were measured from
digitized film mammograms using a computer-assisted thresholding technique; the V measure was obtained from
mammographic images with a previously developed algorithm that measures the standard deviation of pixel
values in the eroded breast region. Generalized linear regression was used to assess associations between OC
use (use status, total duration, age at first and last use, and time since last use) and density measures (square
root-transformed PD, DA, and NDA, and untransformed V).The regression estimates were adjusted for known
breast cancer risk factors. Results: Of the 1,233 women, 184 (15%) never used OC, 952 (77%) were past users,
and 97 (8%) were current users. In multivariable analyses, OC use was not associated with PD (current vs. never:
β=-0.06, 95% CI -0.37,0.24; past vs. never: β=0.10, 95% CI -0.09,0.29), DA (current vs. never: β=-0.20, 95% CI
-0.59,0.18; past vs. never: β=0.13, 95% CI -0.12,0.39), and NDA (current vs. never: β=-0.19, 95% CI -0.56,0.18;
past vs. never: β=-0.01, 95% CI -0.28,0.25). V measure appeared to be higher in past as compared to never users
(β=22.12, 95% CI 0.24,44.00). We observed an inverse association between age at first OC use and the V
measure (<20 years vs. never β=26.88, 95% CI 3.18,50.58; 20-24 years vs. never β=20.23, 95% CI -4.24,44.71;
25-29 years vs. never β=2.61, 95% CI -29.00,34.23; ≥30 years vs. never β=0.28, 95% CI -34.16,34.72, p-
trend=0.03). We found no other significant associations for any of the other OC variables with any of the density
measures. Conclusions: We found no associations of OC use with PD, DA, and NDA. However, we observed a
suggestive positive association of past use with the V measure and that earlier age at first OC use was associated
with significantly greater V.
Keywords: oral contraceptives, breast density, breast cancer