Proteins differ in the number and sequence of amino acids.
A gene mutation changes the sequence of bases in the DNA.
No reasonable person would question thatair pollution is unhealthy, and places people at some increased riskfor lung cancer.The public is often told (by pop writers and even by governmentagencies) that pollution is the cause of an epidemic either of allcancers, or of particular cancers.
Take your questions here first.
Phenacetin: Transitional epithelial (mostly bladder) cancers Anabolic steroids: Liver cancer (this particular risk is relatively small; moreabout "roids" later) Estrogen: Endometrial hyperplasias and carcinomas.
/ Obesity, endogenous hormones, and endometrial cancer risk : ..
AB - Endometrial cancer is a disease of the affluent, developed world, where epidemiological studies have shown that ≥40% of its incidence can be attributed to excess body weight. An additional proportion may be because of lack of physical activity. Alterations in endogenous hormone metabolism may provide the main links between endometrial cancer risk, and excess body weight and physical inactivity. Epidemiological studies have shown increased endometrial cancer risks among pre- and postmenopausal women who have elevated plasma androstenedione and testosterone, and among postmenopausal women who have increased levels of estrone and estradiol. Furthermore, there is evidence that chronic hyperinsulinemia is a risk factor. These relationships can all be interpreted in the light of the "unopposed estrogen" hypothesis, which proposes that endometrial cancer may develop as a result of the mitogenic effects of estrogens, when these are insufficiently counterbalanced by progesterone. In our overall synthesis, we conclude that development of ovarian hyperandrogenism may be a central mechanism relating nutritional lifestyle factors to endometrial cancer risk. In premenopausal women, ovarian hyperandrogenism likely increases risk by inducing chronic anovulation and progesterone deficiency. After the menopause, when progesterone synthesis has ceased altogether, excess weight may continue increasing risk through elevated plasma levels of androgen precursors, increasing estrogen levels through the aromatization of the androgens in adipose tissue. The ovarian androgen excess may be because of an interaction between obesity-related, chronic hyperinsulinemia with genetic factors predisposing to the development of ovarian hyperandrogenism.