THE PERSONALIZED MEDICAL APPROACH TO BREAST CANCER PREVENTION

Angelina Jolie recently announced that she has undergone bilateral mastectomies because she carries genetic variations (BRCA 1/2) that dramatically increase her risk for breast and ovarian cancer. Her story has raised awareness of the potential impact of personal genetic constitution on health and disease, and the options available to respond to this knowledge.

It is important to appreciate that the majority of breast cancer in women is related to environmental exposures and lifestyle factors and NOT to inherited gene mutations. These non-genetic risk factors include the following:

STRONG RISK (Greater than 4 Fold) - dense breast tissue found on mammogram or breast MRI.

MODERATE RISK (2 – 4 Fold)

1. Birth of a first child at a maternal age over 30
2. Post-menopausal obesity

MILD RISK (up to 2 Fold)

1. Poor diets high in processed foods,
2. Moderate to heavy alcohol intake,
3. Long-term use of oral contraceptive pills or postmenopausal hormone replacement,
4. Starting menstruation before age 12 or menopause after age 54

Many of these factors are modifiable. However, family history is not and for women with a strong family history of breast or ovarian cancer, particularly if occurring in pre-menopause, in both breasts, in a male or in numerous family members, the likelihood of an inherited genetic predisposition is high. The most important of these is BRCA. If several specific criteria are met, most provinces will cover the high cost of this test. But BRCA mutations account for only about half of hereditary breast cancers. Several other genetic variants including the CHEK2 Single Nucleotide Polymorphism or SNP are associated with breast and other cancers.

While BRCA is not readily available as a screening test for those who do not meet the above criteria, many of the other cancer risk genetic variants are available privately.

WHAT TO DO IF YOU ARE FOUND TO CARRY A CANCER RISK GENETIC VARIANT?

Preventive mastectomy is not necessary for most, though is a rational option for those who are BRCA positive. In others, attention to lifestyle factors that are known to augment breast cancer risk, increasing the frequency of screening, or using more sensitive screening tests such as breast MRI can effectively reduce the negative impact.