Hormonal Therapy For Breast Cancer
Hormonal therapy for breast cancer nowadays is used for prevention, in the adjuvant setting, neoadjuvant setting and in metastatic disease.
The drugs used, and FDA approved for prevention of breast cancer, are tamoxifen, raloxifen and examestane. High-risk patients are eligible for preventative treatment patients with atypical hyperplasia, strong family history, genetic predisposition, ductal carcinoma in situ, and lobular carcinoma in situ (ER+). Large randomized studies have shown a 50% reduction in development of invasive breast cancer in the patients taking tamoxifen, raloxifen and examestane compared to the control arm (without medication).
Adjuvant hormonal therapy has been around for many years for estrogen receptor positive patients. The first targeted agent developed was in fact, tamoxifen. Adjuvant means in addition to surgery to prevent recurrence of breast cancer. Currently, we have a rather large selection of drugs to choose from, the aromatase inhibitors (arimidex, aromasin, femara), and the selective estrogen receptor modulators (including tamoxifen, evista, fareston as well as the estrogen receptor down regulators like faslodex, which can be used in the adjuvant or metastatic setting).
Interestingly, more recently hormonal therapy has had success in the neoadjuvant (prior to surgery) setting as well, rendering locally advanced ER + tumors resectable. Initially the trials had only post-menopausal patients but recently premenopausal women are being included as well.
In general, the aromatase inhibitors have shown survival advantage compared to tamoxifen, but are associated with joint pain, which interestingly is associated with better response to therapy. Also, within one year of use, the aromatase inhibitors can cause osteopenia/osteoporosis requiring bisphosphonate therapy.
Femara can increase the cholesterol. Tamoxifen and fareston are associated with a slight increased risk of endometrial cancer. Tamoxifen and evista are associated with increased risk of blood clots. All of the hormonal therapies are associated with hot flashes.
Patients on the aromatase inhibitors need to be followed with dexa scans, and patients on tamoxifen and fareston need to be followed with pelvic ultrasound, while patients on femara need to have the lipid profile checked.
What is clear is that the benefits greatly outweigh the side effect profile of the hormonal therapy. By experience, I have noticed that by switching treatments when not tolerated it is always possible to find an acceptable alternative.