Background : 
Health care is a key contributor of national greenhouse gas (GHG) emissions in western countries. Climate change directly threatens populations health around the world, undermine the past 50 years of gains in public health and threatens heath system ability to deliver high quality care. Reducing GHG emissions has become an urgent and significant issue to limit climate change, air pollution and health system dependence to fossil energies. Individual benefit of lung cancer (LC) screening is now well established: it reduces LC mortality in a heavy smoker population about 20% and increases the diagnosis rate of localized and treatable stages.  


Objectives : 
The aim of this study was to evaluate LC management carbon footprint across different stages (localized vs metastatic diseases) 

 
Method: 
We performed a comparative environmental study to assess the carbon footprint of LC management in a thoracic oncology centre (Toulouse University Hospital) at different stages (localized vs metastatic stages). This project has been made in partnership with Monde Nouveau, a design office specializing in carbon and environmental footprint accounting. The methodology used is based on Bilan Carbone®?methodology coupled?with the Life Cycle Assessment (LCA) steps principle.?The Base Empreinte® database was used to evaluate emission factors, and a specific calculator has been made by the design office leaning on a flow mapping for the different health trail. Data from global results of GHG emissions of Toulouse University Hospital (year 2022) and specific data (drugs prescription, medical devices use, and visitors shift) from patients treated for LC in Toulouse University Hospital (year 2022) were used. Direct and indirect GHG emissions (scopes 1, 2 and 3) were considered. 


Results : 
A total of 1293 patients treated for LC in 2022 were included. 245 patients underwent thoracic surgery for localized LC and 566 patients were treated for metastatic disease. The carbon footprint of localized (stage I or II) lung cancer patients who have undergone curative thoracic surgery was estimated at 2.2 tCO2e/patient/year (year of surgery). GHG emissions from the systemic treatment of metastatic cancers (stage IV) were estimated at 9.46 tCO2e/patient/year. The uncertainty interval was 22%. A large majority of the carbon footprint was linked to the purchase and use of medicines and medical devices (respectively 94% and 77% for stage I and IV). GHG emissions due to LC screening were estimated in our institution at 13.5 kgCO2e/patient/year. 

Conclusion: 
The management of localized LC appears to emit 4.3 times less atmospheric CO2 in comparison to metastatic diseases.  When we consider GHG emissions related to LC screening, the difference remains largely in favor of localized stages. LC screening could therefore effectively reduce the carbon footprint of LC management, which in turn would be beneficial for the health of the general population.