Monday, May 19, 2008
I'm a 46-year-old woman. I was premenopausal, and now blood tests indicate post-menopausal (Lupron injection, E2 levels at 12). I was diagnosed three months ago with stage IV breast cancer (two separate tumors in one breast, both ER/PR positive, HER-2 negative). A PET scan indicated widespread metastasis to my bones (spine, pelvis, arms, legs) and a small amount of chest wall metastasis and some remaining affected lymph nodes (23 were removed with 16 positive). I will be changed over to Femara soon (from tamoxifen) and am on Aredia monthly. No chemo is being done at this time. Would a chemo protocol be beneficial at all in delaying further metastasis possibly to other organs?
To summarize, you have an estrogen responsive breast cancer that is no longer manageable with tamoxifen plus Lupron (leuprolide) injections because of progressive bone-based metastases. You are now on Femara (letrozole), an aromatase inhibitor, and Aredia (pamidronate) for prevention of progression in the bones. Presumably, you don’t require Lupron, an ovarian suppression drug, anymore because you have naturally achieved menopause.
First, some women fail to respond to tamoxifen because they don’t metabolize the drug well enough to have enough of the active compound circulating in the blood. Other women initially respond but then stop because of cancer cells that no longer care whether tamoxifen is present. In such women, moving to an aromatase inhibitor such as Femara provides response and is well worth an attempt, considering how much less toxic this strategy is compared to chemotherapy.
Tamoxifen is an estrogen receptor blocker and prevents the uptake of estrogen by the cancer cells. The aromatase inhibitors essentially deplete the body of estrogen in post-menopausal women. Where one might be resistant to one method, response might be had by the alternative method. Certainly, if there is disease progression with all endocrine therapies, then moving on to chemotherapy might be warranted. In addition to chemotherapy, there are also a number of new biologic or targeted therapies now on the market and in clinical trials, which might provide benefit.
Second, I would recommend switching from Aredia to Zometa (zoledronic acid), a more potent bisphosphonate drug that’s more effective at preventing progression of bone-based disease. Your body naturally contains cells that help make bone and cells that help break it down. Cancer cells are like a contractor who very cleverly convinces the laborers (normal bone-destroying cells) to work harder than normal so that the cancer cells can make a home in the bones. Bisphosphonates such as Zometa and Aredia are the union bosses who tell the bone-destroying cells to go on strike, essentially making no room for the cancer cells to find new homes in your bones.