High-risk mammographic parenchymal patterns, hormone replacement therapy and other risk factors: a case-control study

Background Mammographic parenchymal patterns are of particular interest bec ause the denser patterns reduce screening sensitivity as well as increasing breast cancer risk, and because they have been shown to be affected by exo genous oestrogens. Methods We designed a case-control study comprising 200 cases with high-ris k (PZ and DY) pattern and 200 controls with low-risk (N1 and P1) pattern. M ammograms were evaluated according to the Wolfe classification. Results Parity, body mass index (BMI) and current smoking were inversely an d independently associated, whereas late age of menarche and history of ben ign breast disease were positively associated with high-risk mammographic p atterns. Current-users of hormone replacement therapy (HRT) were more than twice as likely to have a high-risk pattern than never-users (OR=2.48, 95% CI: 1.32-4.61). Women who used HRT for more than 5 years were almost three times more likely to have a high-risk pattern than never-users (OR = 2.77, 95% C1:1.11-6.91). Relative to never-users, women who started HRT before th e menopause were more than twice as likely to have a high-risk pattern (OR = 2.53, 95% CI: 1.31-4.87). Conclusions Careful clinical and mammographical follow-up might be appropri ate in women undergoing HRT. The HRT-induced mammographic pattern might be regarded as a new baseline and changes with respect to this new pattern cou ld then be monitored over time.