Gene

Description

Effect on Breast Cancer Risk

Odds Ratio*

Other genes

VDR

Protein product is a receptor that acts as a transcriptional regulatory factor and can stimulate cell differentiation.

Study results are contradictory; association remains unclear.

0.95 CI 0.74-1.20

APC

Tumor suppressor gene that arrests the cell cycle and prevents further cell division and unregulated growth. When mutated the gene is associated with colorectal cancer.

Probably does not play a role in increased risk of breast cancer.

N/A

*Odds ratios for only heterozygous genotype for most common variant alleles are listed (CI= 95% confidence interval).

MANAGING RISK

Individualized Risk Prediction

Understanding that women do not have uniform risk for breast cancer suggests the possibility that they could be stratified into high- or low-risk groups. In theory, such stratification should indicate which women are most likely to benefit from more intensive screening for breast cancer (Figure 4-1). For example, most women would gain no medical benefit from screening before age 40 or from twice-yearly screening, but a small minority could. Conversely, many women could safely be screened for breast cancer only every 2 years, or perhaps even at longer intervals. And even though men can develop breast cancer, it occurs too rarely to warrant mammography screening for men in the general population (Box 4-3). The goal of improving risk assessment is to stratify breast cancer detection strategies with the aim of increasing survival in high-risk women while decreasing cost and complications in low-risk women.23 The challenge lies in developing a more refined understanding of how to assess risk in individual women, and that depends on data from well-designed, large-scale epidemiological studies.

Mammography screening guidelines already take into account two of the most significant risk factors, gender and age. But we could do much



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