Medical confidentiality is sometimes difficult to impose on patient's families, especially in the field of oncology. Here, we describe the case of a 54-years-old woman with a T1N0M0 lung adenocarcinoma. After the diagnosis was made, she advised the medical team not to inform her family about her disease. Although the patient was aware of the high-risk of relapse, she was lost of follow-up after first-line treatment. Five years later, she presented with multi-metastatic recurrence and had to be admitted in an intensive-care unit for severe respiratory failure due to tumor progression. She kept refusing to inform her family, which in the end was contacted by the patient's sister, a few hours before her death. This observation highlights the absolute inviolability of medical confidentiality and led the French Association of Young Pneumologist to initiate a multi-disciplinary symposium on ethical problems raised by the management of patients with lung cancer.