All three found no significant increased risk of breast cancer in women who ever used estrogens. The increased incidence of breast cancer in all these studies may reflect a certain degree of detection bias. Further evidence is needed to confirm this finding. This was compared with the PYLL from hip fracture. However, if breast cancer mortality is in fact unchanged, PYLL from breast cancer would be less than that calculated above.
Current users are at higher risk than past users.
Similar studies have shown a decreased overall mortality, likely due to the decreased CV disease. The available evidence indicates that there does appear to be a reduction of at least this magnitude in cardiovascular mortality. As much as possible, these studies have made adjustments for baseline characteristics which might confound the findings. A randomized trial would help eliminate possible sources of bias. Another important caveat is based on the fact that most women in these studies used unopposed estrogen therapy.