Breast Cancer. Epidemiology. Family History
Epidemiology
The risk factors currently identified for breast cancer do not present a significant potential for control, nor are they as distinct as risk factors for lung cancer and cervical cancer. Other malignancies are associated with breast cancer, and multiple primary tumors of the ovary and uterus may be involved. Patients with endometrial cancer should be carefully screened with annual mammography; similarly, patients with breast cancer should be carefully observed for abnormal uterine bleeding.
Primary care physicians should be aware of a patient’s chances of developing breast cancer and the impact of breast cancer on the general public. Breast cancer is the most common cancer. The chance of developing breast cancer by age 25 is approximately 1 in 20,000; by the age of 60, it is 1 in 24. Another way of impressing this concept is that, in the absence of any major risk factors such as breast cancer in first-degree relatives, the chance of getting breast cancer between ages 30 and 40 is 1 in 1,000; between ages 40 and 50, it is 2 in 1,000; and between ages 50 and 60, it is 3 in 1,000.
Family History
The family history is an important factor in assessing an individual’s risk of a heritable predisposition to breast cancer. One should attempt to distinguish women carrying mutations in breast cancer susceptibility genes, in whom the risk of disease is very high, from women in those same families who have not inherited a susceptibility gene. The possibility of paternal transmission in affected families should be considered. Genetic studies suggest that a significant portion of familial breast cancer may be due to one or more dominantly inherited predisposing genes (see “Genetics and Gynecologic Cancer”).