Pre or Post Menopausal?

I have completed chemo and radiation for a 2 cm, er/pr+, her2 negative tumor.  2 lymph nodes were also found to have cancer.  I am 46 years old and stopped having periods in September after beginning chemo in July.  In February I was determined to be post-menopausal through a blood test that my ob/gyn did.  I started tamoxifen immediately after my last radiation in February.  Why would I not be a candidate for Arimidex now?  What is the determining factor for the 2 different drugs?  I am told it is the pre/post menopausal factor.  I am not really having much trouble on the tamoxifen, just increased hot flashes at night.  Does the Arimidex cause less hot flashes?

[CCF-RN,MSN-rf]

Dear valpal:  Menopause is usually defined as the cessation of menstruation for 1 full year.  By this definition, you may not be classified as post-menopausal.  However, certain blood work can indicate that a person is post-menopausal.  So, from that point of view, you may be post-menopausal.  Arimidex is indicated only for post menopausal women.  If you are indeed post-menopausal, then arimidex may be an appropriate choice. You should discuss this with your oncologist.  You may have hot flashes with either medication, although arimidex is thought to be better tolerated overall.