Population-based estimates of the relation between breast cancer risk, tumor subtype, and family history

• Published in: Breast cancer research and treatment 2009-04, Vol.114 (3), p.549-558
• Main Authors: Welsh, Megan L, Buist, Diana S. M, Aiello Bowles, Erin J, Anderson, Melissa L, Elmore, Joann G, Li, Christopher I
• Format: Article
• Language: English
• Subjects: Adult; Age of Onset; Aged; Aged, 80 and over; Biological and medical sciences; Breast cancer; Breast cancer risk; Breast Neoplasms - diagnosis; Breast Neoplasms - epidemiology; Breast Neoplasms - pathology; Cancer research; Cohort Studies; Epidemiology; Family Health; Family history; Family medical history; Follow-Up Studies; Genetic disorders; Genetic Predisposition to Disease; Gynecology. Andrology. Obstetrics; Heredity; Humans; Mammary gland diseases; Medical sciences; Medicine; Medicine & Public Health; Middle Aged; Oncology; Population genetics; Population-based; Proportional Hazards Models; Receptor, ErbB-2 - biosynthesis; Receptor, ErbB-2 - genetics; Risk; Risk factors; Tumor subtype; Tumors
• ISSN: 0167-6806; 1573-7217
• DOI: 10.1007/s10549-008-0026-1

Objective Many studies that have estimated the breast cancer risk attributable to family history have been based on data collected within family units. Use of this study design has likely overestimated risks for the general population. We provide population-based estimates of breast cancer risk and different tumor subtypes in relation to the degree, number, and age at diagnosis of affected relatives. Methods Cox Proportional Hazards to calculate risks (hazard ratios; 95% confidence interval) of breast cancer and tumor subtypes for women with a family history of breast cancer relative to women without a family history among a cohort of 75,189 women age >=40 years of whom 1,087 were diagnosed with breast cancer from June 1, 2001-December 31, 2005 (median follow-up 3.16 years). Results Breast cancer risk was highest for women with a first-degree family history (1.54; 1.34-1.77); and did not differ substantially by the affected relative's age at diagnosis or by number of affected first-degree relatives. A second-degree family history only was not associated with a significantly increased breast cancer risk (1.15; 0.98-1.35). There was a suggestion that a positive family history was associated with risk of triple positive (Estrogen+/Progesterone+/HER2+) and HER2-overexpressing tumors. Conclusions While a family history of breast cancer in first-degree relatives is an important risk factor for breast cancer, gathering information such as the age at diagnosis of affected relatives or information on second-degree relative history may be unnecessary in assessing personal breast cancer risk among women age >=40 years.