Background: End-of-life (EOL) communication is crucial, particularly for cancer patients. While advanced care planning is still uncommon, we sought to investigate its impact on care intensity in case of organ failure in lung cancer patients. Methods: We prospectively included consecutive lung cancer patients hospitalised at the Grenoble University Hospital, France, between January 1, 2014 and March 31, 2016. Patients could be admitted several times and benefited from advanced care planning based on three care intensities: intensive care, maximal medical care, and exclusive palliative care. Patients' wishes were addressed. Results: Data of 739 hospitalisations concerning 482 patients were studied. During the three first admissions, 173 (25%) patients developed organ failure, with intensive care proposed to 56 (32%), maximal medical care to 104 (60%), and exclusive palliative care to 13 (8%). Median time to organ failure was 9 days [IQR 25%-75%: 3-13]. All patients benefited from care intensity that was either equal to or lower than the care proposed. Specific wishes were recorded for 158 (91%) patients, with a discussion about EOL conditions held in 116 (73%). Conclusions: In case of organ failure, advanced care planning helps provide reasonable care intensity. The role of the patient's wishes as to the proposed care must be further investigated. Clinical trial registration: The study was registered at www.ClinicalTrials.gov with the identifier NCT02852629.