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infections, specifically invasive fungal infections and viral reactivation. The 90-day mortality of cancer patients with severe ARDS remains above 80% [42]. No study is currently available on the benefits of recruitment maneuvers, nitric oxide, and prone positioning in cancer patients. Moreover, it is obvious that cancer patients are deprived of several rescue strategies. ECMO to avoid mechanical ventilation or as a rescue strategy in hematologic patients and after allogeneic SCT has been reported, with poor results and remarkably high complication rates [46, 111, 145] We propose outcome studies on cancer patients with severe ARDS potentially eligible for ECMO by accepted criteria [146]. The use of non-ECMO rescue strategies and of ECMO would be compared to theoretical indications, and the attributable survival of the technique could be estimated. Depending on the results of these studies as well as findings in non-cancer populations, a well-designed prospective ECMO trial might be considered in patients with malignancies. Stem cell transplantation in the ICU Recipients of hematopoietic stem cell transplantation (HSCT) still have a very low survival rate when they become critically ill and require life-sustaining therapies [147]. Although it is usually considered a safe procedure, autologous HSCT still carries a potential for life-threatening complications during the engraftment period, mostly related to the toxicity of high-dose chemotherapy and infections. However, extensive life support while waiting for recovery from neutropenia allows the survival of the large majority of patients. In allogeneic HSCT, however, life-threatening complications are not restricted to the acute toxicity of the conditioning regimen and to infections during the engraftment period, but also extend beyond day 30 because of sustained immunodeficiency as well as specific immune-related complications, both being mainly driven by graft-versus-host disease (GVHD) [148, 149]. It is classically recommended that ICU admission with maximal life support should be offered to patients within the engraftment period, whereas it is more questionable in patients with GVHD [121]. Studies to demonstrate that GVHD is no longer a binary variable (present or absent) but should be better defined by the response to therapy (controlled or stabilized with steroids, uncontrolled, refractory) are warranted. We suggest gathering more data on the trajectory of GVHD in ICU patients and its relation to survival.