by Dr Kathleen Thompson, Author of ‘From Both Ends of the Stethoscope: Getting Through Breast Cancer – by a Doctor Who Knows’
ONE of my readers asked me whether she should have the radiotherapy she’d been offered during her breast cancer treatment. I always advise people to talk to their own doctor, however I did suggest what questions she should ask him.
Nowadays we frequently need to make decisions about our medical treatment, especially if we have cancer. So, not only do we need the facts, but we need to understand them too.
First I suggested she ask what was her specific risk of the cancer coming back if she had the radiotherapy, and what was the risk if she didn’t. This seems an obvious question, but this statistic is not always offered, and we often don’t think to ask.
Your doctor aims to provide the best treatment for you. However, sometimes, particularly, with anti-cancer therapy, the unwanted effects are severe, and so it is good to understand the up-side.
Having requested the information, you need to understand it. A common cause of confusion is the use of a statistical calculation called Relative Risk, because clinical trial results are often expressed using relative risk.
Let me explain: Relative risk is the risk of, say, cancer coming back, in relation to the original risk. So, for example, if your risk of cancer recurrence were 5% with no treatment, and 2% with a certain anti-cancer treatment, then the improvement in relative risk of having the treatment would be 2 divided by 5, i.e 40%. Now, if you were told that the treatment would reduce your risk of cancer returning by 40% you may be persuaded to take the treatment. However if you understood that your actual risk was 5% without treatment and 2% with treatment, you may think differently, particularly if the treatment had side-effects.
So I told my reader to ask what was the improvement in absolute risk for her. The absolute risk, in the example above, would be 3%, ie the difference between 5% with no treatment and 2% with treatment. This is the statistic that most people visualise when they are told of a treatment benefit, and it is much easier to understand.
Fortunately cancer doctors are becoming aware of this potential misunderstanding and try to use absolute risk when explaining treatment benefit. However it is always worth checking what they mean.
Media and internet-sites often quote relative risk when reporting potential new treatments, and these percentages often make a treatment appear misleadingly good.
So what happened when my reader asked to speak to her doctor? She was told that her consultant was away and wouldn’t return to work until after her proposed radiotherapy start date. When she asked to speak to another doctor, the medical secretary was resistant to find anyone for her to speak with. My reader was made to feel that she was being a nuisance asking for this critically important information. She was an assertive lady, and eventually did speak to a consultant, who was only to pleased to provide the information she needed and explain why a course of radiotherapy would significantly reduce the risk of her cancer returning. Having considered the information, she decided to have the radiotherapy.
Sadly there are times when it is necessary to fight for information, but it is so important, so don’t be frightened to persist.
Further Information:
From Both Ends of the Stethoscope: Getting Through Breast Cancer – by a Doctor Who Knows by Dr Kathleen Thompson http://www.amazon.co.uk/dp/B01A7DM42Q
Is This the Best Treatment for me Doctor? Statistics on a Postage Stamp by Dr Kathleen Thompson – Frost Magazine http://www.frostmagazine.com/2016/06/is-this-the-best-treatment-for-me-doctor-statistics-on-a-postage-stamp-by-dr-kathleen-thompson/
