Breast cancer and family history: a multivariate analysis of levels of tumor HER2 protein and family history of cancer in women who have breast cancer.

BACKGROUND: The HER2 gene, located on the long arm of chromosome 17, codes for a protein with the characteristics of a growth factor receptor. In a preliminary study, we reported that high levels of tumor HER2 (erbB-2/neu) protein are associated with a family history of breast cancer (that is, one or more female blood relatives with breast cancer). METHODS: We have now collected a larger number of subjects (94) and performed a multivariate analysis of the independent variables family history of breast cancer, tumor estrogen receptor, age, and tumor DNA index. Family history of breast cancer was assessed by questioning the patient, in many cases by telephone. RESULTS: HER2 levels were significantly higher in women with a family history of breast cancer (p = 0.015, two-tailed t-test). The 27 women with family history were predominantly postmenopausal, mean age 61 +/- 2.3 (mean +/- SEM), versus a mean age of 56 +/- 1.7 for the 67 women with no family history. Of the 27 women with a family history of breast cancer, 13 had a first-degree relative (mother or sister) with the disease. The remaining 14 women had other relatives (grandmothers, aunts, cousins, or a niece) with breast cancer. The results of multiple linear regression analysis, with HER2 as the dependent variable, showed that family history of breast cancer was significantly associated with elevated HER2 levels in the tumors (p = 0.0038), after controlling for the effects of age, tumor estrogen receptor, and DNA index. CONCLUSIONS: The association of family history of breast cancer and elevated tumor HER2 protein suggests that postmenopausal familial breast cancer may be associated with altered HER2 expression.