Hormone positive Breast Cancer

Hello I am eight months post surgery for breast cancer and i have completed rads. My cancer was er+40% and pr+90%  i have been taking tamoxifen since rads but the last two months i have been having zoladex injections (will have ovaries removed early 09) today I switched my meds to femara. My question is is femara showing to be more effective in preventing long term reaccurance than tamoxifen or should i have stayed on tomoxifen for a year or two before changing. My cancer was 8mm, no nodes and no sign of lymphatic invasion. my other question is what is the impact of my pr been more positive than the er? does this determine what medication i should have or does this mean that the hormone therapy  is more effective on er+ cancers?? Does been overweight contribute to hormone positve cancer? Thanks for taking the time to answer my questions

[PaulMD]

Hormone postive cancers whether ER or PR would benefit from anti-hormonal therapy such as tamoxifen or aromatase inhibitors (such as femara).  In clinical studies, Femara and aromatase inhibitors in general have shown superiority over tamoxifen in terms of disese (disease) free survival in hormone receptor positive cancers.  However, the use of femara has been proven in post menopausal cancer patients.  Your situation, wherein femara is combined with chemical ovarian ablation (through zoladex), I believe is still undergoing clinical trials.  The data available today is regarding ovarian ablation combined with tamoxifen which as been shown to be as good as chemotherapy.  

Being overweight, would have an influence in the progression of hormone positive cancers rather than directly causing a cancer cell to be hormone positive.  Fat cells synthesize estrogen, and large amounts of fat cells would mean more estrogen production.