Odds ratios for change in PD from earliest mammogram within levels of earliest PD. No evidence for an interaction of earliest PD and change in PD on breast cancer risk. Odds ratios for change in PD from earliest mammogram within levels of earliest PD. No evidence for an interaction of earliest PD and change in PD on breast cancer risk. A. All women combined. B. Women on HT. C. Never users of HT. Celine M. Vachon et al. Cancer Epidemiol Biomarkers Prev 2007;16:921-928 ©2007 by American Association for Cancer Research