tailieunhanh - Tamoxifen for Prevention of Breast Cancer: Report of the National Surgical Adjuvant Breast and Bowel Project P-1 Study

A woman's hormone balance plays a part in most endometrial cancers. Many of the risk factors for endometrial cancer affect estrogen levels. Before change of life, the ovaries are the main source of the 2 main types of female hormones -- estrogen and progesterone. The balance between these hormones changes during a woman's menstrual cycle each month. A shift in the balance of these 2 hormones toward more estrogen increases a woman's risk for getting endometrial cancer. After change of life, the ovaries stop making these hormones, but a small amount of estrogen is still made in fat tissue | Tamoxifen for Prevention of Breast Cancer Report of the National Surgical Adjuvant Breast and Bowel Project P-1 Study Bernard Fisher Joseph P. Costantino D. Lawrence Wickerham Carol K. Redmond Maureen Kavanah Walter M. Cronin Victor Vogel Andre Robidoux Nikolay Dimitrov James Atkins Mary Daly Samuel Wieand Elizabeth Tan-Chiu Leslie Ford Norman Wolmark and other National Surgical Adjuvant Breast and Bowel Project Investigators Background The finding of a decrease in contralateral breast cancer incidence following tamoxifen administration for adjuvant therapy led to the concept that the drug might play a role in breast cancer prevention. To test this hypothesis the National Surgical Adjuvant Breast and Bowel Project initiated the Breast Cancer Prevention Trial P-1 in 1992. Methods Women N 13388 at increased risk for breast cancer because they 1 were 60 years of age or older 2 were 35 59 years of age with a 5-year predicted risk for breast cancer of at least or 3 had a history of lobular carcinoma in situ were randomly assigned to receive placebo n 6707 or 20 mg day tamoxifen n 6681 for 5 years. Gail s algorithm based on a multivariate logistic regression model using combinations of risk factors was used to estimate the probability risk of occurrence of breast cancer over time. Results Tamoxifen reduced the risk of invasive breast cancer by 49 two-sided p .00001 with cumulative incidence through 69 months of follow-up of versus per 1000 women in the placebo and tamoxifen groups respectively. The decreased risk occurred in women aged 49 years or younger 44 50 59 years 51 and 60 years or older 55 risk was also reduced in women with a history of lobular carcinoma in situ 56 or atypical hyperplasia 86 and in those with any category of predicted 5-year risk. Tamoxifen reduced the risk of noninvasive breast cancer by 50 two-sided p .002 . Tamoxifen reduced the occurrence of estrogen receptor-positive tumors by 69 but no difference in the occurrence of .