Estrogen and Cancer

Posted on Posted in Continuing Education, Homestudy, Seminars, Webinars

486321414_XSThe word “estrogen” actually refers to a family of related molecules that stimulate the development and maintenance of female characteristics and sexual reproduction. The most prevalent forms of human estrogen are estradiol and estrone. Both are produced and secreted by the ovaries although estrone is also made in the adrenal glands and other organs. Estriol is a third form of estrogen that is produced by the placenta and is only synthesized in significant amounts during pregnancy.

The breast and the uterus, which play central roles in sexual reproduction, are two of the main targets of estrogen. The estrogens normally promote healthy cell growth in the breast and uterus. Yet, this same propensity to stimulate cell proliferation can also increase the risk of developing breast or uterine cancer.

The apparent connection between breast cancer and estrogen has been noted for over a century, beginning with the publication of a paper in 1896 by Scottish physician George Beatson. The article, which appeared in the British medical journal, The Lancet, reviewed the case of a 34-year-old woman with advanced breast cancer who lived for four years after her ovaries were removed, a treatment now known as ovarian ablation.

Breast cancer risk increases with menstruation at an early age, late age at menopause, later age at first full-term pregnancy, and few or no pregnancies. Research suggests that the reason may be that these situations result in longer lifetime exposure to estrogen, which promotes cell division in breast tissue and possibly unregulated cell growth, leading to mutations.

BODY FAT & ESTROGEN

According to some studies, body fat and menopause appear to be important factors in the estrogen-cancer connection. Obesity has a complex relationship to breast-cancer risk that differs depending upon menopausal status. In one study published in the International Journal of Cancer, which included 176,886 European women between 18 and 80 years of age, researchers found a 65 percent increase in the risk of breast cancer for

After menopause, the adrenal glands continue to produce small amounts of a steroid called androstenedione, which is converted into estrogens by aromatase in fat tissue. Increased levels of this steroid may be the reason why menopause and obesity are associated with higher estrogen levels and increased risk of breast cancer. It is also believed that excess fat may cause the body to produce more estrogen than is necessary for normal cell growth.

In addition, fat cells secrete the pro-inflammatory chemicals, TNF-alpha and IL-6, either of which can act to increase the production of aromatase, which is directly related to increases in estrogen. Obesity is also associated with greater tumor burden in women diagnosed with breast cancer, higher-grade tumors, and poorer prognosis and/or increased mortality. Weight gain and obesity have been identified as the most important risk and prognostic factors for breast cancer in postmenopausal women. Moreover, the association between obesity and cancer has also been established for colorectal and prostate cancer.

Breast-cancer

Breast Cancer

Posted on Posted in Continuing Education, Homestudy, Webinars

breast_cancer_000014453948Over 60 studies have been published that have examined the relationship between physical activity and breast-cancer risk. Although the majority of studies indicate that physically-active women have a lower risk of developing breast cancer than inactive women, the amount of risk reduction varies widely (from 20 percent to 80 percent). Most evidence suggests that physical activity reduces breast-cancer risk in both premenopausal and postmenopausal women. Women who increase their physical activity after menopause may also experience a reduced risk compared with inactive women.

High levels of moderate to vigorous physical activity during adolescence may be especially protective. For example, a recent prospective study of the activity levels of adolescent girls in relation to their subsequent risk of benign breast disease (a risk factor for later development of breast cancer) found that adolescent girls who — as young women — walked the most were at the lowest risk. The association between adolescent physical activity and breast cancer risk was also examined among women enrolled in the Nurses’ Health Study II. An inverse association was observed between physical activity at ages 14–22 and premenopausal — but not postmenopausal — breast cancer. The association was strongest for women

Awareness may have played a role in the findings of the association between diet intake and breast cancer among Polish women who were ranked according to their level of regular physical activity. The results suggested that a higher intake of vegetables and fruits may be associated with a decreased risk of breast cancer among women who were ranked in either the lowest or highest quartiles of lifetime physical activity. In addition, there was a positive association for sweets and dessert intake among women in the lowest quartile of PA. These findings could be interpreted to suggest that a high intake of antioxidant-rich foods could confer protection in the presence of either a sedentary or extremely active lifestyle. Furthermore, the high intake of sweets in those ranked as least active could be associated with a higher risk for breast cancer.  One additional study found that physical activity performed either before or after cancer diagnosis was related to reduced mortality risk for both breast and colorectal cancer survivors.

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