Reducing your risk of breast cancer

“There are only two types of women today: women who have breast cancer and women who are afraid they are going to get breast cancer.”

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The thought of breast cancer probably scares women more than the spectre of any other type of cancer. With menopause the fear often becomes magnified. Most of us know that the risk of developing cancer increases with age, and we are also concerned about hormone replacement therapy and its possible effect on our breasts. As with any other disease, some things encourage cancer and other things discourage it, and our knowledge of factors influencing cancer in general, and breast cancer in particular, is growing steadily. I hope that after you read this chapter you will feel ready to take a proactive approach to reducing your cancer risk. As you will see, there is plenty of action you can take.

Breast cancer statistics

Breast cancer is the most common type of cancer among Canadian women. The Canadian Cancer Society estimated that 22,300 new cases of breast cancer would develop in 2007, representing 30 percent of all cancers. Breast cancer deaths in Canada in 2007 were estimated at 5300, accounting for 17 percent of all cancer deaths in the country (lung cancer tops the list, followed by breast, then colon, cancer). Sadly, 102 Canadian women die every week from breast cancer. But the good news is that the death rate from breast cancer has decreased in all age groups since the mid-1990s. This is largely because more and more women are having mammograms, allowing for earlier detection (more on mammograms later in this chapter).

Most women want to know what their risk of developing this disease is, and what they can do to prevent it. The following table shows you the risk of developing breast cancer by a certain age.

LIFETIME BREAST CANCER RISK

Age Risk

25 years less than 1 in 1000

50 years 1 in 63

75 years 1 in 15

90 years 1 in 9

These numbers mean that by the age of 50, 1 in every 63 women (1.5 percent) will get breast cancer. By the age of 90, 1 in every 9 women will get the disease (11 percent). As you read these numbers, keep in mind that statistical risks can't be applied to you reducing your risk of breast cancer as an individual. They represent the average risk of the entire population of Canadian women. If you have certain risk factors for breast cancer, such as a family history of breast cancer or a poor diet, these numbers underestimate your risk. Conversely, if you have no risk factors at all for the disease, the numbers overestimate your chances of getting breast cancer.

At this point, you’re probably wondering what factors can increase your odds of getting breast cancer. But before we get to that, I want take you through a short pathology (the study of diseases) course. If you understand the cancer process, it might help ease your worry that cancer is an inevitable disease.

Cancer 101

Simply put, cancer is a disease in which abnormal cells grow out of control. When enough of these cells accumulate, a tumour forms. If the cancer cells are able to break away from the tumour, they can circulate throughout the body and take up residence in another organ, a process called metastasis. But let's go back to the earliest steps in cancer development.

Cancer begins at the cellular level. When we are healthy, our body cells divide every day in order to repair damaged tissues, replace old cells, and grow new tissue. Normal cell growth and division is regulated by internal controls. For instance, if you cut yourself, your body will release messenger chemicals to tell cells in the wounded area to quickly divide and make new cells. Certain receptors on your cells receive the messenger chemicals and then trigger specific enzymes to speed up cellular division. When your wound has healed, the delivery of these messenger chemicals is shut off and cellular life returns to normal. Besides the types of controls that take care of healing, healthy cells are also programmed to die at a certain age so that cellular death will be in balance with new cell growth. But sometimes the process can go awry. Cells don’t stop dividing even though your body tells them to. They take on a life of their own and grow in an unregulated fashion. These cells don’t die when they are programmed to. This is what happens in cancer.

WHAT MAKES A CELL CANCEROUS?

Every cell has a genetic blueprint, called deoxyribonucleic acid (DNA). The DNA of cells contains genes that program cell reproduction, growth, and repair of all body tissues. Sometimes genes can become damaged, and this damage can result in cancer. In essence, there are three ways in which your genes can become faulty:

• A mutation can occur during normal cell division such that the newly formed cell contains an abnormal gene. This can happen randomly or if the cell is exposed to some other agent.

• Cells might be exposed to an environmental agent, called a carcinogen, that harms the DNA. For instance, cigarette smoking is a carcinogen that promotes the development of lung cancer.

• Flawed genes can be inherited from your parents. However, very few types of cancer are the result of inherited genes. Just because you have one damaged gene does not mean you are destined to get cancer. Many processes must take place before a reducing your risk of breast cancer cancer develops. Your body has what are called tumour suppressor genes, which keep an eye out for damaged DNA and halt it in its tracks. But if these tumour suppressor genes become mutated, cells with abnormal genes can multiply at an uncontrolled rate. It is estimated that in 20 to 40 percent of breast cancer cases, a particular tumour suppressor gene (called p53) is mutated. Several genetic mutations are probably needed for breast cancer to develop. Genes that go on to cause cancer are called oncogenes.

Cancer is not explained by genetics alone. Some people who have a family history of a certain cancer never get that cancer. Experts agree that cancer is the result of an interaction between genes and environmental factors, such as diet. For instance, you might have a mutated gene that predisposes you to breast cancer, but because you eat a low-fat diet high in antioxidant-rich fruits and vegetables, you may never get cancer. On the other hand, if you are regularly exposed to pollutants and eat a poor diet, the risk that any faulty genes you carry will catalyze a cancerous growth is increased.