As our Little Star awards remind us every year, people living with and surviving childhood cancer are very special. And our researchers know that these survivors need special attention because they face a different set of problems compared to older cancer survivors.
This month, new research by Cancer Research UK scientists has shown that survivors of childhood cancer are four times more likely than the general population to develop another cancer later in life, and that middle-aged survivors have higher risks of certain cancers such as bowel and bladder cancer.
It might sound like bad news, but this research will help us to save more lives. The increase in risk is mainly due to the intensive treatments needed to cure childhood cancer. For example, we know that radiotherapy and some types of chemotherapy can sometimes lead to cancer many years later. This is because these treatments damage DNA – not just in cancer cells, but in some healthy cells too.
The results of this study will help to improve treatment for today’s children with cancer, as well as sparking ideas for ways to monitor survivors and reduce their risk.
Childhood cancer treatment – benefits and risks
Thankfully more and more children with cancer are growing up to be survivors. Three quarters are now successfully treated, compared with around a quarter in the late 1960s. This huge progress is down to the work of our scientists and other researchers in the UK and around the world.
Children diagnosed with cancer will nearly always need urgent treatment, and no cancer treatment is without risks. For example, radiotherapy kills cancer cells by damaging their DNA and causing them to self-destruct, but it can also damage healthy cells, which over time can go on to become cancerous themselves.
People who have had cancer early in life are more likely to develop new cancers caused by previous treatment simply because they will usually live for longer after they’ve been treated – up to 60 or even 70 years, compared to the relatively shorter remaining lifespan of an older adult cancer survivor. So childhood cancer survivors have a longer ‘window’ in which a new cancer can appear.
Thanks to the British Childhood Cancer Survivors Study, we know that the vast majority of people who survive cancer as children go on to lead perfectly normal lives. This long-term study, which Cancer Research UK funded for over a decade, is helping inform doctors about the problems survivors may face in later life, and how they can be prevented and tackled more effectively.
Tracking survivors to learn about cancer
The new research is based on data from the Survivors Study, which followed nearly 18,000 survivors of childhood cancer who were diagnosed between 1940 and 1991. When these survivors developed a new cancer later in life, the data were recorded through the NHS and flagged to the researchers. This makes it possible to analyse which types of cancer are common in this group of people, and at what age they tend to develop.
With more than 26,000 childhood cancer survivors in the UK, it’s important to know about any extra cancers that are likely to affect this higher-risk age group. For this particular study, the researchers looked at all new cancers diagnosed up until the end of 2006. There were 837 new cases among the 18,000 survivors, almost four times the 216 that would be expected in the same number of people in the general population.
The researchers were especially interested in finding out which cancer types the survivors tend to develop when they’re over the age of 40, when cancer starts to become more common in the general population.
The results showed that cancers affecting the digestive system, genitals and urinary system were the most common in childhood cancer survivors over 40. And survivors who had received radiotherapy treatment to their abdomen had a much higher than average risk of bowel cancer – almost as high as people with a strong family history of the disease.
Other types of cancer that were common in survivors included glioma (a type of brain tumour), breast cancer and bone cancers. Survivors of all types of childhood cancer had an increased risk of cancer later in life, and overall five per cent of survivors had developed a new cancer by age 38, while in the general population it took 54 years to reach this level.
Lessons for the future
On the surface, these results look alarming. But what can we learn from this study?
One thing to bear in mind is that the results are based on people who were treated for their childhood cancer many years ago.
Treatment has changed a lot since 1991, and even more since 1940. One big difference is that radiotherapy is now targeted more accurately, so the treatment causes less damage to healthy cells. This means that the childhood cancer survivors of the future will be less likely to develop new cancers caused by this treatment.
Cancer Research UK is at the forefront of efforts to develop more accurate radiotherapy, and our scientists are also improving treatment for childhood cancer to help prevent long-term side effects. For example, one international trial run by Dr Hamish Wallace in Edinburgh is investigating whether children and young people with Hodgkin’s lymphoma can safely be spared treatment with radiotherapy, which could have a big impact on their quality of life later on.
But beating cancer isn’t just about improving treatments – prevention and early diagnosis are becoming ever more important. The researchers point out that childhood cancer survivors should be encouraged to take advantage of the NHS screening programmes for breast, bowel and cervical cancer, and in some cases they could be offered tailored screening and advice.
Because childhood cancer patients who have received radiotherapy to the abdomen have a higher risk of bowel cancer later in life, it’s likely that they could benefit from extra screening. And with the new flexi-scope technique being added to the bowel screening programme in England, there may be the potential to prevent some of these cancers before they start.
Progress in childhood cancer is a real success story, and the ever-increasing number of survivors is a testament to the efforts of researchers and to the children and families who have taken part in clinical trials to improve treatments.
But the hard work doesn’t stop here – scientists are working towards a brighter future for survivors, so that one day we can truly say we’ve beaten childhood cancer.
Reulen, RC et al (2011). Long-term risks of subsequent primary neoplasms among survivors of childhood cancer. JAMA : the journal of the American Medical Association, 305 (22), 2311-9 PMID: 21642683