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Healthcare professionals sometimes explain things using terms such as benefit and risk.
A benefit is something good or helpful that happens as a result of doing (or not doing) something. For example, a benefit of eating a healthy diet is that you’re less likely to be overweight and therefore less likely to develop diseases such as heart disease, diabetes and some cancers.
A benefit of cancer treatment may be that the cancer is cured or controlled for some time. A benefit can also be that the situation doesn’t get worse. For example, the cancer may stay the same size or grow at a slower rate. Sometimes not having treatment may bring benefits, such as avoiding troublesome side effects that can affect quality of life.
Risk is the chance that something harmful or unwanted may happen as a result of an event or a course of action. It may be as a result of a procedure, test or treatment. Or it may be the result of not doing anything.
Life experiences affect our view of risk and in turn may affect the decisions we make and the action we take. Our views are likely to change at different times in our lives depending on our circumstances.
For example, if you or someone you know has ever been hurt when crossing the road, your perception of the risks associated with this activity may be different from someone who has never experienced this. This in turn may influence your behaviour and may mean that you always choose to cross at a pedestrian crossing.
Risk can be described in different ways. Healthcare professionals commonly use phrases such as ‘low risk’ or ‘high risk’. However, these words can mean different things to different people. Using numbers is sometimes clearer.
Numbers can be expressed in different ways. A doctor may describe risk using percentages (%), fractions or likelihood. So 25 out of 100 can be described as:
When describing risk, doctors sometimes talk about ‘absolute risk’ and ‘relative risk’.
This is the likelihood of something happening to a person. For example, the risk of developing a certain illness in your lifetime may be 1 in 10. This can also be described as a 10% risk.
This compares risk in two different groups of people. An example would be the risk of developing lung cancer in smokers and non-smokers.
The following example may help explain absolute risk and relative risk. This is an imagined example and does not refer to any real medicine or research.
The doctor tells you that:
The absolute risk of developing the disease without drug X is 6%, but with drug X it is 3%. The risk has been reduced by half (from 6 to 3).
A half can also be described as 50%, so the risk has been reduced by 50%. This is the relative risk reduction. The absolute risk reduction is 3% (6% absolute risk – 3% relative risk = 3%).
Relative risk reduction often sounds more dramatic than the absolute risk reduction and is used more often to describe how effective a treatment is.
We can see from this example how the way that risk is expressed may influence decision making.
Understanding risk and how it relates to you can sometimes be difficult to grasp. You can always ask your doctor or nurse to explain things in more detail if you’re not sure.
Doctors may use statistics that tell you what they know about a particular treatment to help you make your decision. Statistics is a way of presenting information (sometimes called data) in numbers. For example, information about a new drug may include data on:
It’s important to remember that statistics are based on large numbers of people. They can’t tell you what is going to happen to an individual person. So if you’re offered a drug that causes nausea (feeling sick) in 50% of people (50 out of 100), you still don’t know exactly whether you will feel sick or not.
Statistics can sometimes be complex and difficult to understand. There are different ways of expressing statistics. These include:
The following example shows how information can be described in different ways. This is an imagined example and does not refer to any real medicine or research.
It shows that both the effectiveness of the treatment and the potential side effects should be considered when making treatment decisions.
A doctor may recommend a new drug to someone who is about to start chemotherapy, as it may help prevent hair loss. Before agreeing to have this medicine, the person may want to know about the side effects, how many people had side effects and whether some people had no side effects.
The doctor tells them that:
In a study of 100 people, the side effects included:
In the study:
There were some rarer side effects too:
Some people had no side effects at all while others had a few different side effects.
The same information can be communicated using a diagram; for example, this can be shown in a bar chart:
Chart showing types of side effects of chemotherapy
View a large version of the chart showing types of side effects of chemotherapy|.
The person may also want to know in how many people the drug prevented hair loss. The doctor explains the results of the study:
Of the 100 people who took the new drug, 70 people found the drug slowed down the hair loss or stopped them from losing their hair, although some still needed a wig.
A total of 10 people had no hair loss, 23 had minimal hair loss, 37 had a lot of hair loss and had to get a wig, and 30 had total hair loss. In all, 67 people still needed to get a wig despite having the drug.
The numbers are a lot to take in, and the information may be clearer to see in diagrams.
The pie chart shows how many people had hair loss and whether they needed a wig.
Pie chart showing wig use and hair loss
View a large version of the pie chart showing wig use and hair loss|.
The person may also want to know more about the overall impact of the side effects on people’s lives.
The doctor tells them:
Of the 100 people who took the new drug, 23 people had all of the more common side effects and felt so tired it really affected their day-to-day lives.
Of those people who had headaches, most found they were quite mild. Only a few had problems so severe that they had to stop taking the medicine.
The person who had the allergic reaction didn’t have the drug again; neither did the people who had a stomach ache.
This can be shown in a ‘smiley face’ diagram :
Diagram showing frequency of side effects
View a large version of diagram showing frequency of side effects|
Having seen these results, one person may decide that they would rather lose their hair than have those side effects. Another person may decide that, as most people felt OK, they’ll try the medicine even though there is still a high chance they may need a wig. There is no right choice.
There are many ways of showing information. Remember that it’s fine to ask for repeated explanations if there’s something you don’t understand.
Content last reviewed: 1 May 2011
Next planned review: 2013
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© Macmillan Cancer Support 2013
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