What you need to know about the BRCA1 and BRCA2 gene… Posted on 19/05/2013

A guest post by Dr. Anna Beaton & Dr. David Cahill

Every mother wants the very best for her family and it is that wish that prompted Angelina Jolie to make a very difficult and personal decision to undergo a preventative double mastectomy.

Cancer is a word that strikes fear into people’s hearts, often producing a deep sense of powerlessness. For anyone to stand by and watch a loved one battle with cancer is excruciating. It no doubt would have been just that for Angelina to watch her mother’s 10-year battle with ovarian cancer, and we can assume that this would have played a significant factor in her decision to undergo the radical surgery.

Angelina was told by doctors that she carries the BRCA 1 gene mutation and has cited the risk factors as told to her by her medical doctors as the main factor in deciding to have the surgery. She was told because of her familial history of cancer, and the fact that she carries the BRCA1 gene she has an 87% chance of developing breast cancer and a 50% chance of developing ovarian cancer.

To tell a mother that she has a 13% chance of living out a cancer-free life with her children and loved ones if she doesn’t have surgery can only be devastating. How could any mother make the decision to keep her breasts when those are the statistics that she is presented with?

But these statistics are misleading.

Cancer is not a disease you just “get”, like being struck by lightening. We all have potentially cancerous micro-tumors in our body. We also have an immune system which, under normal circumstances, is fully equipped to deal with these cells very effectively. Thus whether or not a cancer develops is very dependant upon the level of function of the immune system.

Most breast cancers are not associated with the BRCA1 or BRCA2 mutations. In fact, it has been estimated that overall inherited BRCA1 and BRCA2 mutations account for only 5-10% of breast cancers and 10-15% of ovarian cancers among white women in the United States (1).

Genes (including genes that have been associated with cancer) are either expressed or suppressed, and it is this behaviour that determines our function, and our level of health. Genes DO NOT have the capacity to turn themselves on and off.

It is the ENVIRONMENT of the cell which does this.

Therefore, preventing cancer is something we do everyday, and we do it by the choices we make. It is our lifestyle that determines the cellular environment, and whether we choose to have a pro-cancer lifestyle or an anti-cancer lifestyle is the main determinant. Known factors involved in the development of breast cancer include: Family history, hormonal influences (2), birth control pills (2)(3)(4), hormone replacement therapy (5) (6) (7), obesity (8), level of physical activity (2), alcohol intake(2), dietary fat (9), and our antioxidant and vitamin D levels.

In summary, the fuel and chemistry we put into our bodies, the amount of activity we do, the stress we expose ourselves to and the people we surround ourselves with, all play a vital role.

Proponents of the importance of our genes point to the familial tendencies associated with cancer incidence. Conclusions drawn from such evidence can be overly simplistic, and therefore potentially very misleading.

Broad estimates of breast and ovarian cancer risk associated with BRCA1 and BRCA2 mutations, such as the information given to Angelina, have been calculated from studies of families with a high cancer incidence. The trouble is, not only do family members share genes; they share environments – nutritional intake, belief systems, mental stressors and many other things besides. Therefore, risk estimates that are based on families may not accurately reflect the levels of risk for BRCA1 and BRCA2 mutation carriers in the general population.

In addition, no data are available from long-term studies of the general population comparing cancer risk in women who have the BRCA1 or BRCA2 mutations with women who do not have such mutations.

This renders the estimate as listed above (87%) as grossly misleading.

Twins give us a unique opportunity to examine hereditary factors, as they share the same genes. There are still difficulties because most twins grow up in the same environment, but the researchers endeavour to differentiate between hereditary and environmental factors. One very large study in Scandinavia examined the records of 44,788 pairs of twins. They concluded: Inherited genetic factors make a minor contribution to susceptibility to most types of neoplasms (cancers) (10)

Perhaps the worst aspect of advising someone that they have a “percentage chance” is that it perpetuates the myth that we have no control over whether we develop cancer or not, when in fact we do, everyday. This is disempowering, to say the least, and frankly, when it falsely informs choices involving the removal of perfectly healthy body parts, it is despicable.

We empathize with Angelina and her family, as well as others now in this situation, as this would have been an extremely difficult decision to make. We also believe the empowerment of women to take control of their genetic expression, and for them to make decisions based upon full and complete disclosure of all the facts around cancer, is the only ethical approach.

  1. Campeau PM, Foulkes WD, Tischkowitz MD. Hereditary breast cancer: New genetic developments, new therapeutic avenues. Human Genetics 2008; 124(1):31–42.
  2. PDQ® Cancer Information Summary. National Cancer Institute; Bethesda, MD. Breast Cancer Prevention (PDQ®) – Health Professional. Date last modified 04/30/2009. Available at: http://www.cancer.gov/cancertopics/pdq/prevention/breast/healthprofessional.
  3. PDQ® Cancer Information Summary. National Cancer Institute; Bethesda, MD. Ovarian Cancer Prevention (PDQ®) – Health Professional. Date last modified 04/03/2008. Available at: http://www.cancer.gov/cancertopics/pdq/prevention/ovarian/healthprofessional.
  4. Whittemore AS, Balise RR, Pharoah PDP, et al. Oral contraceptive use and ovarian cancer risk among carriers of BRCA1 or BRCA2 mutations. British Journal of Cancer 2004; 91(11):1911–1915.
  5. National Heart, Lung, and Blood Institute. Women’s Health Initiative. Retrieved April 20, 2009, from: http://www.nhlbi.nih.gov/whi.
  6. Anderson GL, Judd HL, Kaunitz AM, et al. Effects of estrogen plus progestin on gynecologic cancers and associated diagnostic procedures: The Women’s Health Initiative randomized trial. Journal of the American Medical Association 2003; 290(13):1739–1748.
  7. Kotsopoulos J, Lubinski J, Neuhausen SL, et al. Hormone replacement therapy and the risk of ovarian cancer in BRCA1 and BRCA2 mutation carriers. Gynecologic Oncology 2006; 100(1):83–88.
  8. Calle EE, Rodriguez C, Walker-Thurmond K, Thun MJ. Overweight, obesity, and mortality from cancer in a prospectively studied cohort of U.S. adults. New England Journal of Medicine 2003; 348(17):1625–1638.
  9. Prentice RL, Caan B, Chlebowski RT, et al. Low-fat dietary pattern and risk of invasive breast cancer: The Women’s Health Initiative Randomized Controlled Dietary Modification Trial. Journal of the American Medical Association 2006; 295(6):629–642.
  10. Lichtenstein P, Holm NV, Verkasalo PK, et al. Environmental and heritable factors in the causation of cancer–analyses of cohorts of twins from Sweden, Denmark, and Finland. N Engl J Med. 2000 Jul 13;343(2):78-85.

ABOUT THE AUTHORS

Annabeaton

Dr. Anna Beaton
BAppSc(Comp Med) MClinChiro
After graduating from the Royal Melbourne Institute of Technology (2010) with a Masters of Clinical Chiropractic (Distinction), Anna is now a practicing Chiropractor based in Melbourne, Victoria. Anna also volunteers her time with The Australian Spinal Research Foundation.


IMG_0222-1
Dr. David Cahill

BAppSc(Chiro) MACC
Dr David Cahill has been a practicing Chiropractor for the past 20 years. David was the Governor of the Australian Spinal Research Foundation for 11 years, having spent 3 of those years as President. Over the years David has witnessed the simplicity, safety and effectiveness of chiropractic care with people of all ages.

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