Understanding Cancer Risk

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Understanding Cancer Risk

Risk is the chance that an event will happen. When talking about cancer, risk is most often used to describe the chance that a person will get cancer. It is also used to describe the chance that the cancer will come back or recur.

Researchers and doctors use cancer risk to improve the health of many people. One example of this is understanding the risks from smoking. Scientists discovered that smoking increases the risk of lung cancer. They used this knowledge to launch a global anti-smoking campaign to help save lives.

Understanding risk factors

A cancer risk factor is anything that increases a person’s chance of getting cancer. Yet most risk factors do not directly cause cancer. Some people with several risk factors never develop cancer. And others with no known risk factors do.

It is important to know your risk factors and talk about them with your health care team. It will help you make better lifestyle choices to improve your health. This information could also help your doctor decide if you need genetic testing and counselling.

General risk factors for cancer include:

 

You can avoid some risk factors by stopping risky behaviors. These include using tobacco and alcohol, being overweight, and getting multiple sunburns. Other risk factors cannot be avoided, such as getting older. Learn about the risk factors for certain types of cancer.

Risk factors and cancer screening

Understanding your risk for cancer can help your doctor decide whether you could benefit from:

  • A cancer screening test, such as a mammogram or colonoscopy
  • A screening test at an earlier age and more often than routine screening
  • Surgery or medication to lower your cancer risk

People with a strong family history of cancer may consider genetic testing. Your doctor or genetic counselor can talk with you about getting certain genetic tests. They can tell you your risk of getting cancer based on your family history and other risk factors.

 

Understanding the difference between absolute and relative risk

Doctors use absolute risk and relative risk to assess if a person's risk is higher or lower than that of either the general population or a certain group of people.

  • Absolute risk is the chance that a person will develop a disease during a given time. This identifies how many people are at risk for a disease in the general population. 

For instance, consider the statement “1 out of 8 women (12.5%) will get breast cancer in her lifetime.” This describes the absolute risk for the general population of women. It cannot identify the risk for a certain person or group of people. For example, absolute risk cannot show if a group of older women has a higher risk of breast cancer than a group of younger women. 

  • Relative risk compares the risk of disease between two groups of people. It compares one group with a certain risk factor for a disease to another group’s risk. 

For instance, imagine you are comparing the risk of breast cancer among 2 groups of 100 women. But only the women in 1 group have a certain risk factor for breast cancer. The other group of women does not have this risk factor. Researchers keep track of how many people from each group develop cancer over a certain time. Let’s say they find that 2 women who have the same risk factor get cancer. But only 1 woman without this risk factor gets cancer. Then those in the first group have 2 times the risk of the second group. This is a 100% increase in relative risk. The absolute risk, however, would be 2% or 2 out of 100 people.

Patients can use risk measurements to make better choices about lifestyle changes or cancer screening. It is also important to know the difference between absolute and relative risk. For instance, the relative risk in the last example might sound high. It identified a person’s relative risk of developing cancer by 100%. But look at the absolute risk to get a more complete picture. That is, 1 person in 100 compared to 2 people in 100. If you want to compare the research you hear about in the news to your own situation, make sure you find the absolute risk.

Thanks and Regards,
Jack Leo | Managing Editor
Colorectal Cancer: Open Access
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