Tuesday October 16 2012
Breast cancer cases could triple during the next 30 years
The Daily Mail warns of a “breast cancer timebomb due to ‘dramatic’ tripling in numbers of cases predicted by 2040”. The paper says that coping with these numbers will “leave the NHS in crisis”.
The study that this news is based on used existing information about trends in cancer rates, cancer survival and changes in the population in the UK to build a model to predict how these numbers will change over the next three decades.
The news reports in the Mail and The Daily Telegraph focused on breast cancer, but the study in question also looked at bowel, lung, prostate and all cancers combined. The study authors predicted that the total number of cancer survivors in the UK could increase from 2.1 million in 2010 to 5.3 million in 2040. They say this increase will largely be in people aged over 65, and seems mostly due to people surviving longer with cancer and the corresponding expected increase in the elderly population.
The model used by the researchers is based on the assumption that current trends in breast cancer will remain the same, which may not be the case. Changes in screening, risk factors or treatments could affect numbers of cases, or rates of diagnosis or survival.
The study reinforces the importance of long-term planning in order to anticipate the health needs of an ageing population.
Where did the story come from?
The study was carried out by researchers from King’s College London and University College London. It was funded by Macmillan Cancer Support and was published in the peer-reviewed medical journal the British Journal of Cancer.
However, a press release issued by Macmillan Cancer Support on October 16 focused solely on breast cancer – presumably to coincide with Breast Cancer Action Month (run by Breast Cancer Campaign) or Breast Cancer Awareness Month (run by Breast Cancer Care on October 14).
It is noteworthy that this study has led to front page articles in both the Daily Mail and The Daily Telegraph, given that this is the second time both papers have published stories based on this study.
The results of this study were first publicised by Macmillan in a press release on August 20 2012 (Over-65s with cancer 'set to triple by 2040') when the study was published online.
Indeed, the ‘news’ value of this story is further diluted given that the journal published the print version in its September 25 issue.
What kind of research was this?
This was a modelling study that used existing data for England to project how the numbers of cancer survivors in the UK will change up to 2040. As with all models, projections are based on assumptions, and it is not possible to say for certain whether these will prove to be correct. However, the results can still be useful for investigating what might happen in the future, and to help plan for what level of services may be needed.
What did the research involve?
The researchers used national cancer registry data for England between 1971 and 2009, and these data allowed them to calculate how many people alive in 2009 had been diagnosed with cancer in the past. They built computer models to calculate how numbers of people living with cancer in the UK will change using data on the number of new cases (incidence), what proportion of people survive cancer and estimates of how the UK population will change over time based on Office for National Statistics data. The researchers looked at:
- bowel (colorectal) cancer
- lung cancer
- prostate cancer
- female breast cancer
- all cancers combined (excluding non-melanoma skin cancer)
The researchers tested their models on old UK data to see if their projected figures matched actual cancer levels in the past 10 years. They found that their models gave estimates within 5% of the actual rates.
Because the trends in cancer cases and cancer survival that have been seen in the past may change in the future, the researchers used different assumptions about these trends to see what range of estimates for the number of cancer survivors these different assumptions produced.
What were the basic results?
Using the assumption that existing cancer trends will continue between 2009 and 2040, the models predicted that the number of cancer survivors would increase by 1 million in each decade between 2010 and 2040. This would result in 5.3 million cancer survivors in the UK in 2040 (6.2% of the male population and 8.5% of the female population). The rate of growth was predicted to slow over time.
This increase was seen across the cancers tested, for example:
- the number of female breast cancer survivors was predicted to increase from 570,000 in 2010 to 1,683,000 in 2040
- the number of female lung cancer survivors was predicted to increase from 26,000 in 2010 to 95,000 in 2040
- the number of male prostate cancer survivors was predicted to increase from 255,000 in 2010 to 831,000
The exception to such large increases was lung cancer in men, which was predicted only to increase modestly, from 39,000 in 2010 to 42,000 in 2040. While not directly spelled out by the researchers, this is likely to reflect the decrease in lung cancer cases in men in recent years as a result of reduction in the number of men who smoke.
The largest increases in cancer survivor numbers were estimated to be in the oldest age groups and in long-term survivors. The researchers also estimated that almost a quarter of people aged 65 and over would be cancer survivors by 2040. The main cancer types contributing to the rise in this age group are prostate and breast cancer.
The researchers found that varying their assumptions still resulted in increased numbers of cancer survivors over time for most cancers, although the exact numbers differed depending on the assumptions. The highest increases were seen when it was assumed that existing trends in cancer would continue.
How did the researchers interpret the results?
The researchers concluded that improving cancer survival, the ageing population and increasing population size in the UK mean that the number of cancer survivors is “likely to grow substantially in the coming decades”. They say that this means that plans need to be made so that the NHS can cope with the needs of these survivors.
The current study gives projections for the number of cancer survivors in the UK between 2010 and 2040. As with all modelling studies, assumptions about what will happen in the future have to be made, and these assumptions may not prove to be correct.
For example, events in the future may change these trends, such as new treatments or ways of screening for cancer, or changes in demographics.
The authors of the current study acknowledge this uncertainty, and looked at the effect of using different assumptions on their predictions. The main results presented were based on the assumption that cancer trends would stay the same as they have in the past, which the authors note is simplistic, and perhaps optimistic in relation to increasing survival rates. However, they note that this is the scenario that is most likely, based on available data.
Despite the uncertainty around whether these projections will prove to be accurate, this sort of modelling can help the people who plan our health service to decide what sorts of services may be needed in the future.
While some doubt exists about the predictions presented in the study, it is undeniable that the NHS will need to adjust and adapt to changing demographics, disease incidence, treatments and technologies to meet the healthcare needs of the 2040 UK population.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on twitter.