An in-depth review has found that one in four breast cancers could likely be prevented.
Cancer Australia launched a website in December of 2018 that provides detailed information about 68 risk factors that could raise or lower your chances of getting breast cancer. These fall into distinct categories, such as personal, family, genetic, lifestyle and environmental factors.
The risk factors are explained extensively, and are given an evidence classification to explain how strong the evidence is behind the risk, from “convincing” to “unproven or unlikely.”
Some risk factors — like being a woman, getting older, genetics, and family history — are not preventable, and some of them seem downright bizarre on the surface. Your adult height, for instance, offers “convincing” evidence of increased breast cancer risk. But this risk is not causal, meaning your tallness isn’t causing breast cancer directly. Rather, it’s likely due to genetics and environmental factors, as well as some growth processes that breast cancer and height share.
But there are some factors that boil down to the personal choices we make, and shifting those could help decrease our breast cancer risk.
We’ll break down a few of the interesting risks here.
It’s important to note that having one or multiple risk factors doesn’t mean you will develop breast cancer.
Potentially Avoidable Risk Factors
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Being overweight or obese affects breast cancer risk, whether it’s measured by BMI, waist circumference or waist‒hip ratio. But interestingly enough, whether you are premenopausal or postmenopausal affects whether or not that risk is positive or negative.
Breast cancer risk goes up by 12% for every 5-unit increase in BMI after menopause; yet that risk goes down by 7% for every 5-unit increase in BMI before menopause.
The evidence is complex but Cancer Australia posits that obesity affects the levels of particular hormones associated with breast cancer. Premenopausal obesity likely reduces breast cancer risk because it lowers ovarian progesterone production, while postmenopausal obesity likely increases risk because it raises production of oestradiol.
Obesity as a risk factor is deemed “convincing” for postmenopausal women, while evidence shows that it is a “probable” risk factor for premenopausal women.
The more alcohol you consume regularly, the higher your chances of breast cancer.
A typical drink is considered to contain roughly 10 grams of alcohol. Cancer risk increases by about 7% per daily drink increase. So indulging in one drink a day increases risk by 7%; two drinks a day increases your risk by 15%; and four drinks a day increases your risk by 31%, according to the World Cancer Research Fund/American Institute for Cancer Research.
Alcohol consumption as a risk factor is “convincing” for postmenopausal women and “probable” for premenopausal women.
Affluence and Location
If you live in an urban area, have a higher socioeconomic status, and/or live in a developed country, your risk increases. This is likely due to lifestyle factors like diet, obesity, and physical activity, and reproductive and cultural factors like a woman’s age when she has her first child and if she breastfeeds or not. It also could be influenced by better access to medical professionals and screening services.
Smoking and Processed Meats
Cigarette smoke holds over 5,300 chemical compounds, and at least 70 of those are known carcinogens. That it could increase breast cancer risk requires no stretch of the imagination.
It’s not known why processed meat could possibly affect risk, but it may be because processing the meat could produce cancer-causing chemicals, and certain cooking methods could produce them as well.
The evidence for eating processed meats or smoking is deemed “suggestive.” While some evidence has shown an increased risk, there are inconsistent results from other studies or the evidence is limited.
Click “NEXT” to learn about protective risk factors and unproven risk factors.