More genetic variants affect breast cancer risk

Mutations in the BRCA1 gene may not be the only factor that affects the risk of breast cancer in a carrier.  A new study published in the current issue of Nature Genetics found some other genetic variants may modify risk.
 
The study, led by senior author Fergus Couch, Ph.D. of the Mayo Clinic and researchers from 10 other countries, showed that five single nucleotide polymorphisms in the region of chromosome 19p13 were associated with breast cancer risk.
 
Dr. Couch and colleagues first studied 550,000 genetic alterations in the entire human genome in 1,193 carriers of BRCA1 mutations under age 40 who were diagnosed with invasive breast cancer and 1,190 BRCA1 carriers of similar age who were cancer free.
 
The study resulted in the identification of 96 SNPs which may be associated with breast cancer.  Additionally, the researchers further studied these SNPs in 3,000 BRCA1 carriers with breast cancer and 3,000 carriers without the malignancy.
 
As a result, Dr. Couch et al. identified five SPNs associated with breast cancer risk in the chromosome 19p13.
 
Further studies of these SPNs in 6,800 breast cancer patients who did not carry BRCA1 mutations showed that these genetic variants were associated with estrogen-receptor-negative breast cancer. Another study of 2,300 patients found these five SPNs were also linked with triple-negative breast cancer, which is fairly aggressive and accounts for about 12 percent of all breast cancer cases.
 
The researchers said the discovery of these SPNs may help them better understand the mechanisms behind the development of breast cancer, which may help identify BRCA1 carriers who are actually either at a lower or higher risk of breast cancer.
 
Information on whether or not a BRCA1 mutation carrier will develop an aggressive breast cancer helps doctors to decide how the carrier should be protected or treated.
 
BRCA1 is a human tumor suppressor gene and a corresponding protein called breast cancer type 1 susceptibility protein that is expressed in the cells of the breast and other tissue. The protein helps repair damaged DNA and destroy the cell when DNA can't be repaired.  When the gene is disrupted, the body loses its ability to fight breast cancer.
 
People with abnormal BRCA1 gene have up to a 60 percent risk of developing breast cancer by age 90, according to Wikipedia.
 
Breast cancer is expected to be diagnosed in about 175,000 men and women in the United States in 2010 and the disease is expected to kill approximately 50,000 this year in this country, according to the National Cancer Institute.
 
Carrying abnormal BRCA1 gene does not mean a carrier faces a death sentence. Lifestyle modification may reduce the risk significantly.
 
Dr. T. Colin Campbell, a distinguished nutrition professor at Cornell University says in his book China Study that genetics play only a small role in determining breast cancer risk.
 
A new study suggests that red wine compound resveratrol and other natural compounds like xenobiotics, endogenous ligands and other dietary bioactive compounds may help prevent breast cancer through the binding of the aromatic hydrocarbon receptor, which is involved in the development of a variety of cancers.
 
The new study was conducted by Papoutsis A.J. and colleagues at the University of Arizona and is published in the Sept 2010 issue of Journal of Nutrition.

In general, lifestyle factors that may reduce risk of breast cancer include kelp, forsteronia refracta compound, oleic acid in olive oil, restricted calories, apple,  Danggui Longhui Wan, moderate exercise, Turmeric, fish oil, Omega-3 fatty acids, cabbage and sauerkraut, Garlic, Artemisinin, vitamin D, low protein diet, pro-vitamin e,  whole wheat, soy, broccoli, grape juice, home work, high dietary fiber, breastfeeding, green tea mushroom, vitamin c, and sun exposure.

What may increase breast cancer risk include alcohol, high GI diet, adipose fat, bisphenol A (BPA), hormone therapy, cleaning chemical, French fries, childhood obesity, red meat, processed meat, barbecued meat, dietary  fat, grapefruit, Western diet, aluminum salts, low doses of radiation, iron,  antibiotics, calcium, living in a city, and acrylamide.

David Liu and editing by Rachel Stockton