Which of the following are the most important and clinically useful risk factors for breast cancer?

C. Age, gender, and family history in immediate relatives.

 DISCUSSION: The most important risk factors for breast cancer are the patient's age, gender, and a family history of breast cancer in immediate relatives (sisters, mother, daughter). The age-adjusted incidence of breast cancer increases with age. Breast cancer does occur in males, but the disease is far more common in women. Family history is important when breast cancer occurs within the immediate family; history of breast cancer in more distant relatives (grandmothers, cousins, aunts) is less important. In addition, age factors into the risk associated with family history. An affected young primary relative is far more significant as a risk factor than an older relative with breast cancer. The other important risk factor not listed here is a history of breast cancer, either within the conserved ipsilateral breast or in the contralateral breast. Again, age plays an important modifying role; as the age at which breast cancer was first diagnosed increases, the risk of a subsequent second cancer decreases. Although patients with fibrocystic disease are at increased risk for breast cancer, risk concentrates in those patients with fibrocystic disease who show atypical epithelial hyperplasia within breast ducts. Obesity, nulliparity, and alcohol all appear to increase risk slightly and are important to the epidemiologic study of breast cancer; however, the effect of these factors is not sufficient to warrant their use in common clinical practice.