Results
aching joints, muscle aches, vaginal dryness, Pain
Of 100 screened patients 90 completed the trial. Baseline mean LC–MS/MS E2 and E1 were 12 pmol/L (range < 5–57) and 66 pmol/L (< 5–226), respectively. E2 levels measured by immunoassay and LC–MS/MS showed no correlation. E2 and E1 were completely suppressed by letrozole except for one occasion (E1 11 pmol/L at 3 months). Pain, side effects of systemic therapy, vasomotor symptoms, joint and muscle aches, and vaginal dryness increased during letrozole treatment. A high baseline E2 was significantly associated with increased aching joints and muscles, but not with the other side effects.