Bowel and breast cancer screening benefit those with 10 years or more to live
Screening for breast and bowel cancer should only be offered to people who expect to live for at least another 10 years, according to a study of cancer screening benefits.
BMJ Group News
What do we know already?
Cancer screening aims to help people live longer by finding cancers before they have started causing symptoms, at a stage where they may be smaller and easier to treat.
But not everyone benefits from cancer screening, and the benefits are not immediate. If screening finds a cancer that would not have caused problems in your lifetime, you may have unnecessary treatment. This could happen if screening found a cancer that would have grown very slowly, or if you are elderly and have another illness that is more likely to end your life before the cancer has grown.
So most screening programmes are aimed at people who are old enough to be at risk of cancer, but young and well enough to benefit from the effects of screening. People who are expected to live for many more years are said to have a good life expectancy.
What is unclear is how long your life expectancy needs to be to benefit from different types of cancer screening. This new study looked at figures from older studies of breast and bowel cancer screening, to see how long it takes on average for one cancer death to be prevented. They used these figures to calculate the average life expectancy that you would need, in order to benefit from taking part in screening.
Researchers looked at mammography examinations for breast cancer and faecal occult blood test (a test of a sample of poo, also called the FOBT) for bowel cancer.
What does the new study say?
The researchers calculated how long it took to prevent one death from cancer for every 1,000 people screened. They found it took on average just over 10 years before one life was saved from bowel cancer for every 1,000 people screened. The longer people lived after bowel screening, the greater their chances were of benefiting from it. The findings were similar for breast cancer. It took on average nearly 11 years before one life was saved from breast cancer, for every 1,000 women screened.
How reliable is the research?
The results are based on good-quality studies. It’s important to remember that the results are averages, so some people might benefit sooner from screening than others.
What does this mean for me?
In the UK, breast screening is offered to women aged from 50 to 70, and bowel screening using FOBT is offered to everyone aged 60 to 69. People over the age of 70 can choose to have screening, but will not be invited automatically.
It’s your choice whether to have screening for cancer. If you are concerned that your life expectancy may be less than 10 years, and you are unsure whether you are likely to benefit from screening, you could talk to your GP about whether you want to have screening or not.