Breast cancer: What’s the actual risk?
One in nine. Those are the odds. If it were a lottery, we’d all buy a ticket. But this is the breast cancer lottery that tells us one in nine women will develop the disease at some point in their lives.
It’s a chilling statistic. But look around at the women you know. Do one in nine of them have breast cancer? Likely, the answer is no.
A new study from the California Cancer Registry suggests that the figure may be misleading. Depending on your age, your genes and your lifestyle, your immediate risk could be as low as one in a thousand.
“The lifetime risk is scary and not well understood,” says Dr. Cylene Morris, the lead author of the California study. “The risk might be lower than most people think.”
Includes high risks
She and her co-authors set out to determine what a more realistic risk assessment would be. While it may be true that one in nine women develop breast cancer at some point, each individual’s risk is usually lower. One in nine includes people who are genetically predisposed, or are in other higher-risk categories.
Think about ninety-nine newborn baby girls. Eleven of them will develop breast ncer at some point in their lives. That’s one in nine. But each of those eleven have different risk factors for when and if they get the disease.
Consider your age
Age is the most important risk factor. For ninety-nine women at the age of sixty, the risks look different:
- A woman age 60 has a one in 34 chance of developing breast cancer in the next ten years.
- A woman of 70 has a one in 31 chance of developing breast cancer in the next 10 years.
The Canadian Cancer Society suggests using your age to assess your risk for the next decade. That’s a more realistic assessment, which can help healthcare decision-making.
You and your doctor should consider all the risk factors when deciding how much and what kind of cancer screening is necessary. Besides age, there’s childbearing history and your female family history to consider.
Dr. Barbara Whylie of the Canadian Cancer Society, and National Cancer Institute of Canada says the one in nine number is effective for evaluating the disease’s impact on our society and health care system. Knowing that there will be a certain number of cases can influence where research and healthcare dollars will go.
Next page: Assessing individual risk
Asessing individual risk
But it’s not very helpful when you’re trying to assess your individual risk. A newborn baby certainly doesn’t need breast cancer screening, or a mammography. If everybody’s risk was actually one in nine, we should all be running out to get breast cancer screening right now. Yearly mammograms would start at birth. And yearly wouldn’t feel like enough.
“The one in nine is not very meaningful when you’re talking about an individual’s immediate risk. So it’s a statistic we use when talking about policy development when we want to get the attention of government,” says Whylie.
Still a puzzle
So it’s important to place the risks in a realistic frame. For individuals, Morris says it’s important to know your own actual risk, rather than the hypothetical one. Heredity can explain only about five per cent of breast cancer cases. Researchers are still puzzling about exactly what causes most cases. There is some evidence suggesting:
- Women who have one or more children before age 30 may have a lower risk of breast cancer.
- Breast-feeding reduces the risk, but the research is not definitive.
- Frequent alcohol consumption is a known risk factor.
- Poor diet and an inactive lifestyle may also increase risk.
“Good information is something that prompts people to take action,” says Morris. She adds that the one-in-nine statistic can have the opposite effect. “I believe that women, when they are too afraid, may not want to do anything.”