About the Authors

Seth Eckhouse
Richard Sullivan

To whom correspondence should be addressed: E-mail: Richard.Sullivan@cancer.org.uk

Competing Interests

The authors declare that they have no competing interests. The European Commission had no role in the submission or preparation of this article.

Author Contributions

RS designed this study. SE was responsible for data collection, database design, and collation of data. Both authors were involved in the analysis and interpretation of data and writing this paper. RS is the guarantor.