Most clinical trials in cancer screening, prevention, and early detection focus on just three types - and nearly all take place in the global north, according to a new review.
The review, published in BMC Cancer and funded by the National Cancer Research Institute, found that 61% of all cancer screening, prevention, and early detection (SPED) trials focused on colorectal, breast, and cervical cancer. These cancers are responsible for 19.3% of global cancer deaths. However, just 6.4% of trials are done in lung cancer, and 1.8% in liver cancer – and these are responsible for 26.3% of global cancer deaths.
Researchers identified areas of unmet needs around the world to highlight where more research and funding is needed. Some 88% of all SPED trials were conducted in North America, Europe, or Asia, with a lack of trials conducted in Africa and South America and a very low number of trials per head of population In Asia.
With almost half of all cancers in the UK having a potentially preventable cause, this work calls for a greater focus on SPED research, including in the UK.
Results also highlighted that significant disparities exist between the proportion of SPED trials for certain cancer types and their global burden of disease. For example, colorectal cancer accounted for 32.9% of all SPED trials and 9.4% of global cancer deaths, whilst gastric cancers accounted for 1.5% of SPED trials and 7.7% of global cancer deaths.
The study was a collaboration between seven different universities across England and Scotland, including the University of Leeds. It was led by researchers at the universities of Nottingham and Manchester.
Tackling inequalities
Dr Elizabeth Roundhill, Research Fellow in Leeds' School of Medicine, said: "Our research has revealed that even though lung and liver cancers together cause more than a quarter of cancer deaths worldwide, they are less likely to be examined in screening, prevention and early diagnosis (SPED) trials. We also found there was a distinct lack of trials in cancers common in children and young people including sarcomas, blood cancers and brain tumours.
"Importantly, only 12% of SPED cancer trials have taken place in the Global South, meaning that the benefits of implementing SPED interventions in some of the world's most populous regions remain unknown. With almost half of all cancers in the UK having a potentially preventable cause, this work calls for a greater focus on SPED research, including in the UK. We hope that these findings will encourage funders, policy makers and researchers to target resources towards addressing these major health inequalities in the future."
Dr Emma O'Dowd, Consultant Respiratory Physician and Associate Professor at the University of Nottingham, says: "Cancer is the most common cause of death and disability in the UK and the second most common cause globally. Global annual cancer incidence is forecast to rise to 27.5 million by 2040, a 62% increase from 2018. For most cancers, prevention and early detection are the most effective ways of reducing mortality.
"We looked at all trials published between 2007 and 2020 covering cancer screening, prevention, and early diagnosis to map what research had been done by cancer type, trial focus and geographical area, and to highlight research gaps.
"Over 117,000 papers were identified, and 2888 trials were included. There were disparities in terms of geographical location, type of research conducted and a clear focus on a small number of cancer types. We hope that this important piece of work can be used to guide and prioritise future trial funding."
