{'fraction_non_alphanumeric': 0.042392566782810684, 'fraction_numerical': 0.02032520325203252, 'mean_word_length': 5.197841726618705, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Predictors of Breast Density Change After Hormone Therapy Cessation: Results from a Randomized Trial

Background: Postmenopausal hormone therapy cessation is associated with a decrease in mammographic density (MD), but it is unknown whether this effect is modified by woman-level characteristics. We investigated whether we could identify characteristics of women who were most likely to experience a decrease in MD due to hormone therapy cessation. Methods: Postmenopausal hormone therapy users with a prior screening mammogram (n = 1,168) were randomized to continue hormone therapy or to suspend hormone therapy for 1 month or 2 months before their next screening mammogram. We estimated relative risks (RR) and attributable risks with 95% CIs of a ≥7.5% decrease in percentage MD (%MD) versus no change associated with hormone therapy cessation, stratified by age, body mass index (BMI), parity, and other factors. Results: Hormone therapy cessation increased a woman's likelihood of experiencing a ≥7.5% decrease in %MD by 30% (95% CI = 1.03–1.7), but we found little evidence of effect modification by age, race, BMI, change in BMI, baseline %MD, parity, family history of breast cancer, hormone therapy type, or duration of hormone therapy use. Conclusions: Woman-level factors do not appear to explain why some women experience a decrease in %MD following hormone therapy cessation and others do not. Impact: We were unable to identify subgroups of women who are more likely to experience a decrease in MD due to hormone therapy cessation; other factors, such as genetic factors, may be important determinants of hormone therapy–related changes in MD. Cancer Epidemiol Biomarkers Prev; 20(10); 2309–12. ©2011 AACR.