Tamoxifen and Breast Cancer
:
- Genral Information
- This year approximately 180,000 women will be diagnosed with breast cancer, and about 50,000 of them will die of the disease.
- 1 out 15 women develop breast cancer between the ages of 60-79
- At age 60, about 17 out of every 1,000 women are expected to develop breast cancer within five years
- What causes breast cancer is not entirely clear but many of the risk factors have been identified
- Risk factors include:
- overall exposure to estrogen
- genetic predisposition
- Age
- Age of first birth
- post-menopausal therapy
- certain benign breast conditions
- Estrogen’s effects
- Estrogen has both helpful and harmful effects
- The main tissues of action are:
- Brain
- Breast
- Bone
- Uterus
- Heart/Liver
- Estrogen’s desirable effects:
- Bone - maintain density
- Uterus - nourish a fetus
- Breast - lactation
- Liver/Heart - regulate cholesterol (HDL, LDL) and decrease incidence of coronary heart disease
- Brain - may support memory and delay or ease Alzheimer’s disease
- Estrogen’s negative effects:
- Breast - promotes breast cancer
- Uterus - promotes uterine cancer
Post-menopausal Alternatives
- No therapy
- No relief of menopausal symptoms
- increased risk for osteoporosis and heart disease
- Estrogen replacement therapy
- decrease risk of osteoporosis and heart disease
- increased risk of breast cancer, uterine cancer and blood clots
- Herbal extract therapy
- Little information of mechanism of action and efficacy
- No regulation of herbal remedies
- Tamoxifen
- decrease risk of osteoposrosis
- decrease risk of breast cancer
- increase risk of uterine cancer and blood clots
- possible increase in liver cancer and liver dysfunction
- Tamoxifen
- Tamoxifen has been tested for various application since the 1960’s and has been used as an adjuvant treatment for breast cancer patient for 20 years
- The risks and side effects of tamoxifen are fairly well established
- Tamoxifen has both estrogenic and anti-estrogenic effects
- SERM (selective estrogen receptor modulator)
- The Breast Cancer Prevention Trial (BCPT)
- Conducted by the National Surgical Adjuvant Breast and Bowel Project (NSABP)
- Five year, double blind study
- 13,388 women participated (all were considered high risk for development of breast cancer)
- 40% - ages 35-49
- 30% - ages 50-59
- 30 % - ages 60 and older
- women were accepted into the study based on certain risk factors:
- age 60 or older
- number of first-degree relatives diagnosed with breast cancer
- number of breast biopsies
- number of children and age at first birth
- age at menarche and menopause
- Lobular carcinoma in situ (LCIS)
- Results of study:
Condition Placebo Tamoxifen
Non-invasive breast cancer 59 31
Invasive breast cancer 154 85
Bone fractures 71 47
endometrial cancer 14 33
pulmonary embolism 6 17
deep vein thrombosis 19 30
Heart disease 28 31
Deaths from breast cancer 6 3
- Mechanisms of anti-estrogenic activity:
- Alternative coactivator
- Alternative response element
- Two types of estrogen receptor
- Study of Tamoxifen and Raloxifene (STAR)
- Raloxifene may provide protection against breast cancer and uterine cancer
