BACKGROUND: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.
BACKGROUND: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. METHODS: Serum dehydroepiandrosterone (DHEA), estrone (E1), and estradiol (E2) levels were prospectively measured in 47 breast cancerpatients 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. RESULTS: 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). CONCLUSIONS: 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.
Authors: Mengyuan Du; Xujuan Yang; James A Hartman; Paul S Cooke; Daniel R Doerge; Young H Ju; William G Helferich Journal: Carcinogenesis Date: 2012-01-20 Impact factor: 4.944
Authors: Jennifer Gjerde; Jürgen Geisler; Steinar Lundgren; Dagfinn Ekse; Jan Erik Varhaug; Gunnar Mellgren; Vidar M Steen; Ernst A Lien Journal: BMC Cancer Date: 2010-06-21 Impact factor: 4.430
Authors: Cheryl L Rock; Shirley W Flatt; Gail A Laughlin; Ellen B Gold; Cynthia A Thomson; Loki Natarajan; Lovell A Jones; Bette J Caan; Marcia L Stefanick; Richard A Hajek; Wael K Al-Delaimy; Frank Z Stanczyk; John P Pierce Journal: Cancer Epidemiol Biomarkers Prev Date: 2008-03-06 Impact factor: 4.254