Cancer starts when cells with somatic mutations that stimulate cellular division spread.[1] These mutated cells create an abnormal protein or no protein at all. The information for an abnormal protein is different from the information for a normal protein, and this difference is dangerous and can cause cells to multiply uncontrollably.[2]

Breast cancer is a disease in which certain cells in the breast become abnormal and multiply without control or order to form a tumor. [3] It is, simply, cancer of the breasts.

Most women with breast cancer have no family history of the disease.[4] Most breast cancers are genetic changes that occur in breast cells during a person’s lifetime. A small percentage of all breast cancers, however, are hereditary. Hereditary cancers are results of inherited gene mutations. They tend to occur earlier in life than noninherited cases and are more likely to involve both breasts.[5]

My maternal grandmother, great grand mother, and great great aunt and my paternal great aunt and great grand mother have all had breast cancer. They had mild forms of it, yet I am concerned that since such a high percentage of my relatives have had it, that I am also at risk. This topic is very personal and important to me, and I enjoyed the opportunity to learn more about breast cancer genetics.

Background and History

The earliest known medical document is what is known as the Edwin Smith Papyrus. It dates back to 1600 BC and was discovered in 1862 by Edwin Smith. The document discusses diseases in Ancient Egypt including breast cancer.[6]

In Ancient Egypt the treatment for breast cancer was to burn the tumors found in the breast with an instrument called "the fire drill." They tried to remove the tumors, but, for the most part, they were not able to stop the cancer. On the Edwin Smith Papyrus, the ancient Egyptian doctor of breast cancer writes, "There is no treatment."[8]


Breast cancer is documented throughout history, yet it was not until Europe in the 17th century that doctors were able to understand the nature of breast cancer. These European doctors linked the tumors in the breast to the lymph glands in the armpit.[10]

In the early 18th century, Jean Louis Petit and Benjamin Bell performed the first surgeries removing the lymph nodes, breast tissue and breast muscle in order to remove the cancer from the body and fight its spread.[11]

William Stewart Halsted followed in their footsteps and performed complete mastectomies in 1882. His procedure is known as the Halsted radical mastectomy. This procedure was popular throughout the 20th century and is still common today.[13]

In 1952 the American Cancer Society created the Reach to Recovery program, which is the first and most important program in the history of breast cancer treatment and advocacy. The Reach to Recovery program was a group of women who would go to hospitals to support patients who had just had mastectomies. This group continues to operate today.[15]

In the 1970's breast cancer awareness began to grow rapidly. More and more organizations have been formed to increase knowledge and awareness of breast cancer. While breast cancer survival rates have, for the most part, increased over the last twenty years, it is still too common and kills too many women.[17]

There have been a great many improvements in the treatment of breast cancer, but there is still a large amount of research yet to be done.

Here are some interesting (and frightening!) statistics about breast cancer:

  • Breast cancer is the most common cancer among women, excluding skin cancer.[18]
  • In 2009, an estimated 192,370 women in the United States were diagnosed with invasive breast cancer, while 62,280 women were diagnosed with non-invasive breast cancer.[19]
  • It is estimated that 40,610 deaths (40,170 women, 440 men) from breast cancer will occur this year.[20]
  • Only lung cancer accounts for more cancer deaths in women.[21]
  • The average risk for a woman to contract breast cancer is 12%.[22]
  • If a woman has a first-degree relative who had breast cancer, the woman’s risk is double the average woman's risk.[23]
  • If a woman has two first-degree relatives who had breast cancer, the woman’s risk is 5 times the average risk.[24]
  • An estimated 5 to 10 percent of all breast cancers are hereditary.[25]

Explanation and Connections

BRCA1 and BRCA2 are major genes related to the hereditary of breast cancer.[26] BRCA1 stands for BReast CAncer gene one, and BRCA2 stands for BReast CAncer gene two.[27] The function of these genes is to keep breast cells growing normally and to prevent any cancer cell growth.[28]

When a person has mutations or abnormalities in these genes, she has a higher risk of contracting breast cancer, ovarian cancer, and several other types of cancer.[29] For example, women with the BRCA mutations have a 50% to 85% chance of developing breast cancer and a 15% to 40% chance of developing ovarian cancer.[30]


Abnormal BRCA1 and BRCA2 genes account for about 10% of all breast cancers.[32]

The way that cancer risk is inherited depends on the gene involved. For example, mutations in the BRCA1 and BRCA2 genes are inherited in an Autosomal Dominant pattern. In other cases, the inheritance of breast cancer risk is unclear.[33]


Click here to go to a wonderful sight that teaches about cancer genetics and explains breast cancer genetics in more detail. It is very interesting, and I highly recommend it!

In addition to specific genetic mutations, there are also many personal and environmental factors that can influence a person's risk of developing breast cancer.[35]

Some of the Risk Factors include:

  1. Gender: Women account for 99% of breast cancer cases.[36]
  2. Age: The risk of contracting breast cancer increases after a person turns 50.[37] Screen_shot_2010-05-29_at_10.50.40_PM.png[38]
  3. Ethnic background: People with Ashkenazi Jewish descent have a higher risk of contracting breast cancer.[39] Screen_shot_2010-05-28_at_5.34.42_PM.png[40]
  4. Family History: Women who have a first degree relative or an other close relative with breast cancer have an increased risk of developing breast cancers.[41]
  5. Medical History: Women with previous breast cancer have a high risk of contracting it again.[42]
  6. Hormones: An excess of estrogen may contribute to breast cancer risk because of its natural role in stimulating breast cell growth. Women who had their first menstrual period before the age of 12 or experienced menopause after age 55 have a slightly increased risk of breast cancer. Also women who had their first child after age 30 have a higher risk of contracting breast cancer. Each of these factors increase the amount of time a women’s body is exposed to estrogen, so they also increase the possibility of getting breast cancer. The removal of woman’s ovaries and breast-feeding reduces breast cancer risk.[43] estrogen-cartoon.gif[44]
  7. Hormone Replacement Therapy: HRT reduces discomforts of menopause symptoms (such as hot flashes), yet it has many harmful side affects, including an increased risk at contracting breast cancer.[45]
  8. Birth Control Pills (Oral Contraceptives): There is a slight increase in the risk of breast cancer among women taking birth control pills[46]
  9. Obesity: The risk of getting breast cancer increases when you are obese.[47]
  10. Alcohol: Alcohol consumption is associated with increased breast cancer risk. Researchers are, however, unsure whether reducing alcohol consumption would decrease breast cancer risk.[48]
  11. Tobacco Products: The use of tobacco products increases the risk of contracting breast cancer.[49]

Here are some ways to reduce your risk factors:

  1. Physical Activity: Physical Activity, especially strenuous physical activity, decreases the risk of breast cancer.[50]
  2. Balanced Diet: Eating a balanced diet of healthy foods and maintaing a healthy weight decrease the risk of breast cancer.[51]

Here are some connections to what we have learned in class:

It was really helpful to fully understand DNA Replication, Transcription, and Translation while researching breast cancer. I could understand how a mutation in DNA could be copied into so many other cell's DNA and then be transcribed into RNA and translated into proteins.


It's really terrifying and interesting how all of this is connected!!

I tried to find the type of genetic mutation the BRCA1 and BRCA2 mutation are, but I did not learn exactly what type of mutations they are.

The inheritance of BRCA1 and BRCA2 mutations are thought to be Autosomal Dominant.
Here is a pedigree of a family with Hereditary Breast Cancer:


Here is a pedigree of a family with Huntington's Disease:

Both of these diseases have Autosomal Dominant inheritance patterns. It is important, however, to remember that someone with the BRCA1 and BRCA2 mutations does not necessarily get breast cancer. Breast cancer has many more external factors than Hutington's Disease does, yet they do have connection with their similar inheritance pattern.

Social and Ethical Implications

There are blood tests and genetic testing one could take to test for BRCA1 and BRCA2 mutations.[54] My mother could take this test to see if she is has the inherited mutations, yet she does not want to take them. She feels that if she knew that she had the mutation, she would still not be able to reduce the risk of contracting the cancer. She would rather not know if she has it. There are psychological risks and benefits of the genetic tests results, but it is also very expensive (several hundred to a thousand dollars).[55]

If you have taken the test and learn that you have the genetic mutation, here are your options:

  1. Screening: This will not change the risk of developing cancer, but will help find the cancer early when it is easier to treat. Some screening methods include mammography, clinical breast exams, and magnetic response imaging (MRI).[56]
  2. Prophylactic Surgery: This surgery removes as much of the risky tissue to reduce the risk of contracting breast cancer. Bilateral prophylactic mastectomy, the removal of healthy breasts, is another option, yet it does not guarantee against developing breast cancer because not all at-risk tissues are removed.[57]
  3. Risk Avoidance: Avoiding the risks that can increase cancer, such as drinking and smoking. These factors are listed above.
  4. Chemoprevention: The use of natural or synthetic substances to reduce the risk of developing cancer. For example, the drug Tamoxifen can reduce the risk of contracting breast cancer by about 50 percent. Another drug called Raloxifene can also reduce the risk of developing invasive breast cancer by about 50 percent in postmenopausal women.[58]

Potential Futures

Research to better understand the link between genetic mutations and breast cancer is ongoing.[59] Other genes probably play a role in the development of breast cancer, for women both with and without a family history of the disease, and there is still a lot more to learn about these genes.[60] More research is needed to understand how gene mutations can increase breast cancer risk and to find other genes that may increase a person’s risk of breast cancer.[61]

I have been trying to embed this video, but unfortunately it is not working. Click here to learn about some recent research to help stop the inheritance of breast cancer. The procedure discussed in the video is called Pre-implantation Genetic Diagnosis. It is extremely interesting and worth watching!

Endnotes and Citations

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