Category Archives: Breast Cancer

Celebrity Cancer Series: Angelina Jolie

In 2013, Angelina Jolie, the American actress, filmmaker and humanitarian, and receiver of numerous awards, made the difficult decision to undergo a preventative double mastectomy. Two years later, Jolie underwent another preventive surgery—this time, her ovaries and fallopian tubes were removed. Jolie lost her mother, grandmother and aunt to cancer. A simple blood test revealed that Jolie carries the BRCA1 gene mutation, giving her an 87 percent risk of developing breast cancer and a 50 percent risk of developing ovarian cancer. Learning this, Jolie took her health into her own hands.

With an estimated 25 000 Canadian women being diagnosed with breast cancer in 2015, breast cancer continues to be the most common cancer among Canadian women and the second leading cause of death from cancer. Choosing to undergo preventive surgery is not a light decision; however, a woman’s lifetime risk of developing breast or ovarian cancer  greatly increases if she inherits a harmful mutation in BRCA1.

There is a common misconception that women “inherit the BRCA1 cancer gene” and that this will eventually cause a woman to develop cancer. Contrary to this belief, we need the BRCA1 gene. This gene produces proteins that help repair damaged DNA and ensures the stability of our genetic information in our cells. However, when this gene is mutated and the protein is not produced or is not functioning properly, DNA damage may not be repaired properly causing the genes in our cells to accumulate more changes that can lead to cancer.

Although 55-65 percent of women who inherit a harmful BRCA1 mutation will develop breast cancer and approximately 39 percent will develop ovarian cancer, testing positive for this mutation does not reveal that an individual will certainly develop cancer; it reveals only that they are at an increased risk. It is important to remember that other characteristics of a women can increase or lower one’s cancer risk, such as one’s reproductive history and physical activity levels. Still, less than half of breast cancer cases can be explained by well-established risk factors. Ongoing cancer research efforts here at Queen’s University will hopefully allow us to understand and treat this disease better, and eventually improve our chances for preventing this disease.

This article was written by Carmen Chan, a MSc candidate in the Department of Public Health Sciences at Queen’s University, and a Canadian Cancer Society Research Information Outreach Team (RIOT) member.

Using genetics to discover how ethnicity affects breast cancer

Breast cancer is the most common cancer in women, causing more deaths worldwide than any other form of cancer. What causes breast cancer is extremely complex and can include both genetic and environmental factors. To complicate matters further, breast cancer isn’t a single disease, but actually contains several different subtypes, each of which are genetically different from one another. This creates a challenge in trying to make a generalized treatment or prevention strategy. An even bigger challenge is the fact that the genetics behind breast cancer can also differ among various ethnic groups. However, researchers at Queen’s University are trying to address these complex challenges and I jumped at the opportunity to help out.

My research focuses on investigating the role of single nucleotide polymorphisms (SNPs), which are mutations in genes, and how they contribute to uncontrollable cell growth, an important feature of cancer. I am interested in seeing whether these mutations, when present in genes associated with cell growth, can increase the risk of developing breast cancer. I am trying to understand how these mutations differ amongst various ethnic groups.

It is interesting to note that genes associated with the highest risk of developing breast cancer are actually less commonly mutated. In fact, only about 15% of breast cancer cases result from mutations in “high risk” genes, such as BRCA1/2. The rest, almost 85% of breast cancer cases, occur as a result of the accumulation of many mutations or SNPs in what we call “low risk” genes. These “low risk” genes would not pose a major threat on their own, but when combined together with hundreds of such small mutations, can lead to the development of breast cancer.

Let me give you an analogy to help explain this. In an orchestra, if the conductor (“high risk” genes) isn’t good at giving direction, the music would sound terrible. But if one musician (“low risk” gene) in an orchestra isn’t playing well, it would still sound okay and the audience probably would not notice. Now imagine many musicians (many “low risk” genes) are not playing well. Similar to having a bad conductor, the music would be totally awful.

Our lab at Queen’s University has previously identified and helped to analyze more than 750 such “low risk” but highly common SNPs. Moving forward, in order to look at these mutations in different ethnic groups, we needed to look at a large number of patients with different ethnic backgrounds. To do so, we are working together with researchers from the University of British Columbia and Genome Quebec to help us with this massive undertaking. Our results will then be combined with results from researchers from 26 different countries. Collaboration is key to helping enhance our knowledge of breast cancer and more specifically, how genetics in different ethnic groups contribute to the development of this disease.

It is an amazing experience to work with so many talented researchers from around the world to help answer a very complex question relating to breast cancer. I can’t wait to see what type of results unfold. My hope is through this collaborative effort, the underlying differences in breast cancer genetics would be better understood and prevention and treatment can be tailored to a specific individual. Stay tuned to our blog as I update the findings from my research and others on this topic.

This article was written by Saadul Islam, a PhD candidate in the Department of Epidemiology at Queen’s University, and a Canadian Cancer Society Research Information Outreach Team (RIOT) member.