| Breast cancer is the most common malignancy tumor in women. In recent decades, the incidence of breast cancer is increasing all over the world, and rank the first with 2% increased rate per year in many countries or areas. More than 1 million new patients annually have been accounted for 20% of female primary malignancy tumor. Most nations of Asia including China, which was once the low incidence area, are now dramatically increasing with the higher rate than high incidence areas and than the average increment level of the world. Especially in some economic flourishing regions and big city, the incidence was resided the first female malignant tumor. Up to now, the etiology and mechanism of breast cancer are obscure. Some risk factors for breast cancer such as reproductive factors, dietary, environment factors, spiritual and mental factors have been established by epidemiological study. However, in recent twenty years Chinese women have experienced the change of the living style in different way, the female reproductive, grows, the mental state and living environments have also alternated. The breast cancer incidence increasing continuously indicated that the risk factors and expose levels vary possibly. As a hormone-dependent tumor, endogenous sex hormones play an important role in breast cancer happen and development. Epidemiological study indicated that long-term and high-level estrogen expose was the important risk factor for breast cancer. Estrogen involved in tumorigenesis is based on the general concept that it can increase mitotic activity in the breast epithelium as a promoter; on the other hand, estrogen metabolites can bind to DNA and trigger damage as a tumor initiator. The enzymes that involved estrogen biosynthesis and catabolism determined the product and quantity of estrogen. Cytochrome P450cl7 (CYP17) and cytochrome P450 19 (CYP19) of Cytochrome P450 system are the limit-rate enzymes in estrogen biosynthesis; one of the family members in sulfotransferases, sulfotransferases 1A1 (SULT1A1), is the key enzyme involved estrogen inactivation metabolism and bioactivation transition of procarcinogens. Genes encoded CYP17(17-a hydroxylase, 17, 20-lyase), CYPI9 (aromatase) and SULT1A1 (phenol sulfotransferases) are the common low penetrancegenes. These low penetrance genes involved in a wide variety of functions including steroid hormone metabolism, detoxification of environment carcinogens, DNA damage repair are associated with breast cancer happen. Polymorphism of low penetrance genes, one of the important material foundations for genetic susceptibility, is associated with breast cancer occurrence in special population. At the same time, existence of polymorphism may endow individuals sensitive to some special environment factors. Heredity gene and expose factors may take together in evolvement of mammary glands cancerous conversion. In present study, we conducted a multigenic and multivariate case-control study to investigate the prevalence tendency, changes of risk factors, and the roles of estrogen and estrogen-metabolizing genes in development of breast cancer on epidemiological and molecular epidemiological aspect. And provided the foundation for clarifying the etiology and mechanism of breast cancer, screening susceptibility population, establishing effective strategy in prevention and treatment and early diagnosis. The mainly methods and results in our study are as follows.First, we collected the mortality data of breast cancer in 1988~2001 in Hubei province. Incidence and mortality data in 1998-2002 in Qiaokou district of Wuhan city from breast cancer registry were also collected by typical survey method. The results indicated: (1)the crude mortality of breast cancer in both rural and urban areas in Hubei province was increased consistently by 1.53% and 6.51% per year, respectively. The order of mortality proportion of breast cancer in urban areas was ranked from the 13th in 1997 to the 4th in 2001, and from the 17th to the 5th in rural areas at the same time; (2)From 1988 to 2002, the crude... |
PDF Full Text Request