BACKGROUND: Although first-degree female relatives (FDFR) of women with breast cancer are at increased risk for the disease, little is understood about how familial diagnosis impacts health behaviors and what personal factors predict such changes.

METHODS: Six hundred women, ages 18 and over with a FDFR recently diagnosed with breast cancer, were interviewed after the diagnosis and again in 6 months. Participants self-reported changes in physical activity, fruit and vegetable consumption, fat consumption, alcohol and tobacco use. The effect of baseline demographics, health status, perceptions of relative's disease severity, personal risk, control over the disease and the effect of lifestyle behaviors on risk was assessed in relation to behavior changes.

RESULTS: Forty-two percent reported improving one or more behaviors. Perception that the behavior was a risk factor for breast cancer was positively associated with change for all behaviors except smoking. Poor health status, obesity and perception of control over breast cancer were associated with improvements in physical activity, fruit and vegetable consumption and fat consumption.

CONCLUSIONS: Diagnosis of breast cancer in a first-degree relative can provide motivation to improve health behavior. Educational interventions highlighting the importance of these behaviors in reducing breast cancer risk and promoting health in general may be effective in this population.