Content area
Full Text
REVIEWSTHE NURSES HEALTH STUDY: LIFESTYLE AND HEALTH AMONG WOMENGraham A. Colditz and Susan E. HankinsonAbstract | The Nurses Health Study has grown from a simple questionnaire-based study initiated in 1976 to a rich resource of information collected over 29 years. Important details about lifestyle have been collected throughout the study and, as the study has progressed, blood samples and DNA from buccal cells have been collected and stored. Tumour samples havealso been collected from participants who developed cancer. Through analyses that integrate information from these various sources we are advancing our understanding of the causes of cancer and the potential for prevention.To avoid potential biases in retrospective studies and to establish a base for the evaluation of both the risks and benefits of oral contraceptives after they became widely used, Frank Speizer, of Harvard Medical School, initiated the Nurses Health Study (NHS) in 1976 (see TIMELINE). Speizer and colleagues enrolled 121,700 women aged 3055 with the primary goal of investigating the long-term health consequences of oral-contraceptive use. Modelled after the British Doctors Study of health consequences of smoking the first study to establish a causal relationship between smoking and a range of cancers, as well as heart disease among men1 the NHS aimed to address growing concerns regarding the long-term health effects of oral contraceptives. These drugs had been introduced to the United States (US) market in the 1960s and became widely used, and several side effects had already been documented. The researchers were particularly interested in assessing the association between oral-contraceptive use and breast cancer, because an increased risk was observed with the use of oral contraceptives in retrospective, casecontrol studies2. Uniquely, the NHS cohort of women were asked to complete questionnaires every 2 years (FIG. 1), which allowed participants to update information on oral-contraceptive use and reproductive variables that are related to breast cancer risk. This very large study of women was the first of this size to include updated data collection on lifestyle to relate to cancer risk.Background on the Nurses Health StudyThe researchers initially attempted to study the association between oral contraceptives and cancer in pilot studies that involved the wives of physicians. These had unsatisfactory response rates, but subsequent pilot tests among registered nurses proved sufficiently successful to justify a...