Non-surgical therapies for resected and unresected pancreatic cancer in Europe and USA in 2003-2014: A large internationals population-based study

The role of chemotherapy in the treatment of pancreatic cancer (PaC) has been well-established, while radiation plays ambiguous roles. This international large-scale population-based study aimed to investigate the real-world application of chemotherapy and radiotherapy for resected and unresected PaC in Europe and USA. Population-based data from multiple European national cancer registries and the US Surveillance, Epidemiology and End Results (SEER)-18 database during 2003-2014 were analyzed. Temporal trends and geographical variations in the application rates of chemotherapy and radiotherapy were quantified using age standardization. Associations of treatment with demographic and clinical characteristics were assessed using multivariable logistic regression. A total of 141,533 PaC patients were analyzed. From 2003-2005 to 2012-2014, chemotherapy administration rates increased in most countries and more strongly among resected patients, while radiation rates were generally low with a slight decline or no obvious trend. In 2012-2014, 12.5% (Estonia) to 61.7% (Belgium) of resected and 17.1% (Slovenia) to 56.9% (Belgium) of unresected patients received chemotherapy. Radiation was administered in 2.6% (Netherlands) to 32.6% (USA) of resected and 1.0% (USA) to 6.0% (Belgium) of unresected patients. Strong temporal and geographical variations were observed. Patterns and strengths of associations of treatment administration with various demographic and clinical factors differed substantially between resected and unresected cancers and varied greatly across countries. Conclusively, administration of chemotherapy but not radiotherapy for PaC increased during the last decade in Europe and USA. Treatment rates were low and the uptake strongly varied across countries, highlighting the need for standardization in PaC treatment to improve patient care.