Estrogen receptor positive breast cancer is the most common type of breast cancer and
anti-estrogen therapy has been shown to be very effective in preventing recurrence. Side
effects of anti-estrogens are due to estrogen deprivation and include hot flashes, mood
changes and vaginal dryness/pain. Vaginal symptoms including pain, dryness, itching, bleeding
after intercourse and frequent urinary tract infections have been reported to cause
significant morbidity in postmenopausal women and higher in breast cancer survivors on
anti-estrogen therapy. Treatment options include vaginal lubricants, Replens etc but
unfortunately many women continue to have persistent symptoms. Local estrogen has been shown
to be effective in post menopausal women (Estring or Vagifem) for their vaginal symptoms.
There is a concern of using this in women with breast cancer given it may increase their
blood estrogen levels. Studies done so far show have shown controversial results but majority
of them report that blood estrogen levels do not change significantly. The major drawback of
the studies was the sample size and inadequate accrual. The most recent trial reported showed
no significant change in blood estrogen levels in women with breast cancer treated with
aromatase inhibitors (anti-estrogen therapy) and were on vagifem for their vaginal symptoms.
The authors reported results in 26 patients and reported no significant change in blood
estrogen level. We propose to study the change in blood estrogen level when postmenopausal
women with breast cancer who are currently on aromatase inhibitors are treated with Estring
for their vaginal symptoms.