Dear suziejane: 1)In hormone receptor positive breast cancer many studies over the years have shown survival benefit with the use of hormone therapy. The earlier studies had shown this benefit with Tamoxifen. More recently with the advent of aromatase inhibitors (such as Arimidex) this benefit was seen with these medications in post-menopausal women. The percentage improvement depends on your baseline risk of recurrence but, in general, the hormonal treatment prevent close to half of the recurrences that otherwise would have occured.
2) Indole 3 Carbinol is a substance that is being studied to see if it can help prevent cancer. It is found in certain types of vegetables. These include broccoli, cabbage, cauliflower and Brussels sprouts. There are no data to support using it in place of hormone therapy for treatment of breast cancer.
3) The jury is still out on the answer to this question. Estrogen-like substances that are found in plants such as soy, are much weaker than the estrogen found in the body. However, how much would be too much is not clear. Some oncologists feel that normal dietary sources of plant estrogen-like substances are probably safe, however, supplements containing these products are often avoided as the dosages of estrogen-like substances may not be known or controlled given that supplements are not regulated by the FDA.
My mother took Tamoxifen for 5 years and her breast cancer came back as ovarian cancer 13 years after that. I took it in the trial because I have 3 daughters and had seen many family members die from breast cancer, to see if it prevented breast cancer. My cancer showed up 8 years after I stopped the Tamoxifen. My younger sister had it 1 year before me, she was 48. She had not taken any drugs. Turns out, we have the BRCA2 mutation. She and I chose bilateral mastectomies and I had total hysterectomy. We choose to fight and live.