The word ‘risk’ means the chance that an event will happen. In cancer, risk is often used to describe the chances of getting cancer and the chances of it recurring down the track. A combination of genes, lifestyle and environment can affect this risk.
A ‘risk factor’ is anything that increases your likelihood of developing a health disorder, such as cancer. It doesn’t necessarily directly cause cancer. Doctors do not know the exact causes of cancer, but there are risk factors that can increase your chance of developing it. Some people with definite risk factors never actually end up developing cancer. Some do. Some risk factors can be reduced, some can not be altered at all. Conversely, there are also ‘protective factors’, which are linked to lower risk of cancer.
Health advocates often discuss ‘modifiable’ risk factors when there are things you can change about your lifestyle or health care that will reduce your risk, such as smoking. Non-modifiable risk factors are things that can’t be changed, such as age, ethnicity and gender. Public health campaigns are often aimed at preventative measures for modifiable risk factors. If there are possible risk factors identified, screening programs, such as mammograms, bowel and cervical cancer screening, can be used earlier than recommended.
There are two different types of risk assessments. An ‘absolute risk’ is your chance that you will develop a disease over a particular period time. But this figure can’t be then applied to a smaller, more specific population.
Whereas a ‘relative risk’ compares the risks of acquiring a disease between two groups of people, by looking at both groups’ risk factors. This measurement might appear quite high, but the absolute risk will give you a more complete, accurate picture of YOUR general risk.
To demonstrate the difference, we’ll use a simple example about breast cancer, given we know that the BRCA genetic mutation is hereditary. Stated in terms of relative risk, a woman is 3x times more likely to get breast cancer if she has a family history than a woman who has no family history. In absolute risk terms, an Australian woman has a 7.8% overall lifetime chance of getting breast cancer compared to a woman whose mother, sister, or daughter has had breast cancer, giving her a risk of between 15-20%
It is important to know your risk factors and talk about them with your health care team. Sometimes this can ultimately improve your health by determining whether there are genetic tests and counseling you need, or different lifestyle choices you can make.
Some general risk factors that we already know about include older age, a personal or family history of cancer, using tobacco, obesity, alcohol, some viral infections (such as HPV), specific chemicals, and exposure to radiation (such as sun UV).
It’s important, however, not to confuse ‘risk factor’ with ‘cause’. The former increases the risk of disease and doesn’t require the illness to exist; the latter actually directly causes illness, and only exists when the actual illness has occurred. Before the illness exists, the likely cause is often only a risk factor.
Translated, this means that if you have had cancer risk factors identified, it doesn’t mean you are destined to develop cancer. Also if you have cancer, it doesn’t mean that you had identifiable risk factors that you could have modified to prevent the cancer. There is so much unknown, and so much that you don’t have any control over.
So if you’re confused, take some questions to your healthcare team:
- What risk factors do I have? How do they affect my risk of cancer?
- What can I do to lower my risk of cancer?
- If I act on modifiable risk factors, will I reduce my chances of getting cancer?
- What cancer screening tests do you recommend? And how often should I have them?
Then remember “the most important risk factor for cancer is growing older.” This is something that you have no control or influence over. So find out your family history, see your doctor for concerning symptoms, turn up for your cancer screening tests, and try to tune into what your body needs and look after yourself.
If you have further questions, please contact us at Rare Cancers Australia.
Authored by Dr Emily Isham