Background

Global cancer incidence is forecast to rise to 27.5M by 2040,a 62% rise from 2018.Whilst considerable progress is being made in systemic therapy,prevention and early detection are the most effective ways to reduce mortality.The aim of this study was to map trials in screening,prevention and early diagnosis for all cancer types in order to identify areas of unmet need and highlight research priorities.

Method

A systematic mapping review was conducted to evaluate all clinical trials assessing any intervention focused on cancer screening,prevention or early diagnosis for any tumour type. NCRI portfolio,EMBASE,PubMed and Medline were searched for relevant studies published between 01/01/2007 and 01/04/2020.Studies were exported into Covidence software and double-screened. Data were extracted and mapped according to tumour site,country of study,and intervention type.

Results

A total of 117,701 abstracts were screened,5157 had full text reviews and 2888 were included. Overall,52% of trials focussed on screening,24% prevention,20% early diagnosis and 4% on a combination. Colorectal,breast and cervical cancer comprised 61% of all studies.When global cancer incidence and mortality were compared to number of trial publications important disparities were seen:cervical cancer trials are 5-fold higher than disease incidence/mortality and colorectal 3-fold higher.By comparison,only 6.4% of research activity involved lung cancer and 1.8% liver cancer, tumours that account for 18% and 8.3% of cancer deaths respectively.The number of studies varied markedly according to geographic location;88% of the studies were based in North America, Europe or Asia compared with 2% in Africa and 1.5% in South America.

Conclusion

This study provides a comprehensive overview of the published trials covering cancer screening,prevention and early detection over a 14-year period.There are clear disparities in the proportion of research conducted between tumour types,and according to geographic location and hence population.The findings will help drive future research priorities so that resources can be apportioned according to the major challenges faced in the area of screening, prevention and early diagnosis of cancer.

Impact statement

This study provides the first global summary of trials for cancer screening,prevention and early diagnosis which can be used by funders,policymakers and researchers to guide and prioritise future work to address both research and funding gaps,aiming to improve cancer outcomes.