Changes in serum estrogen levels in women during tamoxifen therapy
Abstract
Tamoxifen is considered an antiestrogen against breast cancer, yet it has known estrogenic side effects. We hypothesized that long-term administration of tamoxifen may significantly increase circulating estrogen levels in women with breast cancer. Serum dehydroepiandrosterone (DHEA), estrone (E1), and estradiol (E2) levels were prospectively measured in 47 breast cancer patients before and during tamoxifen therapy for 2 years. Differences in baseline and peak hormone levels during treatment were compared, and significance was determined by paired Student's t test. Mean DHEA levels increased by 133% from 61 mg/L to 142 mg/L (P <0.001) and mean E2 levels increased by 239% from 28 pg/mL to 95 pg/mL (P <0.05). Mean E1 levels increased by 264% from 42 pg/mL to 153 pg/mL (P = 0.06). Long-term tamoxifen therapy can be associated with increased serum levels of DHEA, E1, and E2. Elevated serum estrogens may explain tamoxifen's estrogenic effects and may represent a mechanism for the development of drug resistance.
References
Citations
Reproductive steroid hormones and recurrence-free survival in women with a history of breast cancer.
Related Concepts
Related Feeds
Breast Cancer: Chemo-Resistance
Some cancers are difficult to treat and aggressive including the "triple-negative" breast cancer. This type of cancer is chemoresistant even before chemotherapy begins. Here are the latest discoveries chemo-resistance in breast cancer.