Paul Pharoah, co-lead CRUK Cambridge Centre Ovarian Cancer Programme, based in Department of Oncology and Department of Public Health and Primary Care, and Nora Pashayan, Department of Applied Health Research, UCL discuss the challenges of earlier detection of cancer in an article in the journal Science published today.
The article was written following a talk given by Professor Pharoah on the challenges of early detection at The Early Detection of Cancer Conference in Stanford, US last year.
In the article, the authors caution that earlier detection and an apparent increase in survival may not always signify improved prognosis because some patients will die at the same time despite earlier detection of their tumour, and some patients will die of other causes.
They go on to discuss the particular issues with screening – where an early detection test is given to large groups of the healthy population with the intention of detecting cancer at an early stage when it can be cured and before it has spread.
The success of screening for various cancers is dependent on how quickly different tumours grow, when a tumour is likely to spread, how sensitive screening is at detecting small tumours, and how often screening occurs.
Using breast screening as an example, they point out that to detect the most aggressive cancers early enough to be curable, screening would need to detect tumours smaller than currently possible and would need to take place more frequently than at present. They also highlight the risk of overdiagnosis and overtreatment if early detection tests are not able to distinguish between fast-growing aggressive tumours and slow-growing indolent tumours.
They suggest priorities are to develop screening tests that can identify which small tumours are likely to spread or have already spread, and to carry out randomised controlled trials on the most promising early detection tests to assess how effective they are at improving health outcomes.
Professor Pharoah said: “There is huge potential for new technology for developing tests that can detect cancer earlier. There are many challenges to be overcome before such tests can be used routinely for cancer screening.”
Reference:
Nora Pashayan and Paul DP Pharoah The challenge of early detection in cancer Science 08 May 2020
