Estrogen levels while on Tamoxifen

I  was diagnosed with invasive lobular cancer (1cm) in April. I had a lumpectomy in May and 7 weeks of radiation.  I have been taking tamoxifin (tamoxifen) since June. My estrogen level was 216 in August, and now in October is 260.  My oncologist wants me to begin Lupron, and my gynecologist thinks that the Tamoxifen is working and the estrogen will level down.
My question:  Is the tamoxifen working.  Do I need to take Lupron to "dry up my ovaries?"  What are the side effects.
I have not had a period since the end of June.  I have been managing my hot flashes with vitamins e and c.  They are not a  problem.  I am 48 and have 2 children.

Thankyou.

[CCF-RN,MSN-JS]

Dear Jane, There has been some question as to what role ovarian ablation (drying up the ovaries) has in the treatment of early stage breast cancers.  This treatment has shown benefit in the treatment of metastatic breast cancer, so they are now studying it in terms of adjuvant treatment for early cancers.  The reason for doing it would be to further decrease the estrogen available to estrogen-receptive tumors.  In pre-menopausal, or perimenopausal women, the use of Lupron would be to speed up the process of decreasing estrogen.  We don