Factors that increase endogenous estrogen production or reduce the binding of estradiol to SHBG may increase a woman's risk of developing breast cancer later in life.

A cohort study is under way in New York City to evaluate how levels of endogenous reproductive hormones influence the risk of breast cancer. The study, in which approximately 15,000 women are being recruited, utilizes a prospective design in which volunteers are asked to provide repeated specimens of serum during the period 1985-1992. A case-control study nested within the cohort is planned by which specimens from all cases arising in the population and from a randomly selected sample of time-matched controls will be analyzed and compared. As of December 31, 1989, 13,609 volunteers had donated blood specimens, about 50% of whom had already donated more than once. Of the 187 incident breast cancer cases who are expected to arise in the cohort before the end of 1992, 77 have been detected thus far.

To investigate whether hair dye use increases the risk of breast cancer, a case-control study was conducted among patients attending a screening center in New York City. The study group consisted of 398 breast cancer cases identified at the screening center between 1977 and 1981, and 790 randomly selected controls screened during the same period. Subjects were interviewed by telephone to obtain information on known risk factors for breast cancer, along with a complete history of hair dye use detailing type of dye, color, duration, frequency, and temporal periods of use. Most subjects (77%) had used hair dye at least once, 38% of the subjects at least 100 times. However, little increased risk of breast cancer was found among hair dye users. The adjusted odds ratio for ever having used hair dye was 0.8 (95% confidence interval 0.6-1.1), and there was no evidence of a trend in risk with increasing number of hair dye uses. The results were the same whether all past exposures were considered or only exposures more than 10 years before disease. Breast cancer risk did not increase with increasing intensity of exposure, as measured by frequency of use or darkness of color. No effect was seen for different types or colors of dye, or for use during different periods of reproductive life. Although personal hair dye use was unrelated to breast cancer risk, there was an adjusted odds ratio of 3.0 (95% confidence interval 1.1-7.8) for 5 or more years of work as a beautician. Overall, the results of this study, taken in conjunction with the findings of other epidemiologic studies, do not implicate hair dye use as an important cause of human breast cancer.

Results from the randomized trial underway in the Health Insurance Plan of Greater New York to determine the efficacy of periodic screening with mammography and palpation of the breast have been examined to determine the effect of screening on racial differences in breast cancer survival rates. Consistent with experience in general populations, the control group showed a lower five-year survival rate among non-White women with breast cancer than among White women. In the study group, 65 per centIn this paper, information from the randomized control trial to test the efficacy of screening for breast cancer* being conducted by the Health Insurance Plan of Greater New York (HIP) is utilized to examine differentials in survival rates among non-White women compared with White following diagnosis of breast cancer.Briefly, the situation in the general population is that Black women with breast cancer have a markedly poorer fiveyear relative survival rate** from breast cancer than White women as exemplified in Several explanations might be advanced for the relatively poor survival rates from breast cancer among Black women: e.g., differentials in diagnostic delay because of variations in recognition of signs and symptoms and care seeking behavior; quality of care; or the underlying biological course of breast cancer due to genetic or other host factors. Results from the HIP study discussed below suggest that secondary prevention programs may be an effective approach to changing the poor survival rate of Blacks. The HIP StudyThe HIP study's design, methodology, and findings for all races combined have been reported extensively in the literature.4 The investigation was initiated toward the end of 1%3 to determine whether periodic screening with clinical examination and mammography results in reduced breast cancer mortality among women aged 40-64 years at time of entry. Women in this age group who were members of the Plan, a comprehensive prepaid group practice with a wide spectrum of socioeconomic groups of enrollees, were allocated through a stratified random procedure to study and control groups, each consisting of 31,000 individuals. Study women were offered screening examinations; the 65 per cent who appeared for the initial examination were offered three additional examinations at annual intervals unless earlier follow-up or biopsy was indicated; all but a small proportion (12 per cent) had at least one additional annual examination. Control women received their usual medical care which during the 1960s did not emphasize other early detection methods, e.g., breast self-examination.Screening ended in 1970 and follow-up of the tested cohorts of the study and control women, including those who are no longer enrolled in HIP, has continued to date to

This paper deals with a long-term prospective study of breast cancer to determine the value of periodic screening for this condition, which also incorporates epidemiologic objectives. The methodology of the study, the variables included, and preliminary observations based on detected cases are presented. THE difficulties in conducting prospective studies on comparatively low incidence diseases are so severe that they are rarely undertaken for a specific condition. This holds for breast cancer despite the fact that an estimated 6 per cent of the women develop the disease during their lifetime and about one in five of the deaths from cancer among women is attributable to this condition. However, an opportunity has recently presented itself to incorporate epidemiological objectives related to breast cancer in a long-term prospective study whose main purpose is to investigate the value of periodic breast cancer screening. This paper presents the methodology of the study, the variables included, and preliminary observations based on the breast cancer cases detected in the early stages of the investigation. Before proceeding to this discussion, a brief review of where we are in understanding the epidemiology of breast cancer is in order. THE SEARCH FOR RISK FACTORS IN BREAST CANCERThe outstanding characteristic of the search for risk factors in female breast cancer is the lack of success in identifying specific parameters that are strongly associated with the incidence of the disease. The unifying element in these efforts is a hormonal hypothesis, whether the investigation is concerned with socio-