Sex Hormones and Breast Cancer

The NYU Women’s Health Study was the first study of its kind to conclusively demonstrate that higher levels of endogenous estrogens after menopause are associated with an increased risk of breast cancer. In a study published in 1995, researchers of the Women’s Health Study reported that postmenopausal women with higher levels of estrogen (estradiol and estrone) had an increased risk of developing breast cancer. In 1997, they reported that postmenopausal women with higher levels of androgens (male sex hormones, including testosterone, androstenedione, and DHEAS) also had an increased risk of breast cancer, probably because these hormones are converted into estrogens in the body. These findings were confirmed in 2002 in an international analysis involving eight similar studies. The results provide strong evidence that increased levels of both estrogens and androgens are associated with an increased risk of breast cancer in postmenopausal women.

Sex Hormones and Endometrial Cancer

Sex hormones have long been believed to affect the development of endometrial cancer. Researchers of the Women’s Health Study examined the effect of estrogens and androgens on endometrial cancer risk. Results showed that the risk of endometrial cancer was increased in postmenopausal women with higher levels of estrogens and androgens in the blood. Some of this work was carried out in conjunction with collaborators involved in similar studies in Sweden and Italy. The results of these studies provide direct evidence of an association between higher levels of circulating estrogens and androgens after menopause and an increased risk of endometrial cancer.

“Lifestyle” Hormones and Cancer

There is increasing awareness that health problems result from a sedentary lifestyle and being overweight. These health problems may be due in part to hormonal aberrations that accompany being overweight. NYU Women’s Health Study researchers have studied the effect of hormones that are influenced by excessive weight, notably C-peptide and insulin-like growth factor 1 (IGF-1), on several types of cancer. We found that in women less than 50 years of age, IGF-1 was associated with an increased risk of both breast and ovarian cancer. Increased levels of C-peptide, which is indicative of higher insulin levels in the blood, were associated with an increased risk of endometrial cancer. High levels of C-peptide, insulin, and insulin-like growth factors (IGFs) were associated with an increased risk for colorectal cancer. Decreasing the levels of these hormones in the blood by implementing lifestyle or medication changes may decrease the risk of these cancers.

Diet and Cancer

Researchers of the NYU Women’s Health Study examined the relation between risk of breast cancer and intake of meat, animal products, fat, protein, fruits and vegetables. They found that women who ate more meat had a higher risk of developing breast cancer than women who had less meat and saturated fat in their diet. In another study, Women’s Health Study researchers found that higher levels of carotenoids, anti-oxidants found in colorful plants, were associated with a decreased risk of breast cancer. This is evidence that a diet high in fruits and vegetables and low in meat and saturated fat might confer protective benefits against the development of breast cancer.

NYU Women’s Health Study researchers also studied the effects of diet on the risk of developing colorectal cancer. They found a decline in the risk of developing colorectal cancer with increasing intake of fish, shellfish and dairy products in a woman’s diet. In another study, researchers found that higher levels of folate, which is abundant in fruits and vegetables, were associated with a reduced risk of colorectal cancer. Thus, a diet high in fish, dairy products, fruits and vegetables may help prevent the development of colorectal cancer.

Aspirin and Cancer

It is thought that aspirin, due to its anti-inflammatory power, may have an effect on the risk of cancers whose development is influenced by chronic inflammation. Researchers of the NYU Women’s Health Study examined the role of aspirin in such cancers, particularly ovarian and lung cancer. Consistent with findings of others, they found that women who used aspirin three or more times a week for a period of six months or longer were less likely to develop both ovarian cancer and lung cancer compared with women who did not use aspirin at all. Regular aspirin use may be protective against the development of these cancers in women.