Author Contributions: Mr Botteri had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Botteri, Lowenfels, Maisonneuve.
Acquisition of data: Botteri, Iodice, Raimondi.
Analysis and interpretation of data: Botteri, Iodice, Bagnardi, Raimondi, Lowenfels.
Drafting of the manuscript: Botteri, Bagnardi.
Critical revision of the manuscript for important intellectual content: Iodice, Raimondi, Lowenfels, Maisonneuve.
Statistical analysis: Botteri, Iodice, Bagnardi, Raimondi.
Administrative, technical, or material support: Botteri, Iodice, Raimondi.
Study supervision: Lowenfels, Maisonneuve.
Financial Disclosures: None reported.
Additional Contribution: We thank William Russell-Edu, BSc, DipLib, librarian at the European Institute of Oncology, for his valuable library assistance. He did not receive any compensation for his help.