Relationship of body mass index with aromatisation and plasma and tissue oestrogen levels in postmenopausal breast cancer patients treated with aromatase inhibitors

Our unique data do not support a lack of effective aromatase inhibition in overweight patients or therefore a need for alternative therapy. The higher levels of estrogens in overweight postmenopausal breast cancer patients before and during aromatase inhibition may be due to effects of BMI on oestrogen metabolism rather than aromatisation.