In cancer patients with acute respiratory failure (ARF), early adequate therapy is associated with better outcomes. We investigated the performance of the DIRECT approach, which uses criteria available at the bedside at admission to the intensive care unit (ICU), to identify causes of ARF in cancer patients. This cohort study included cancer patients with ARF of determined aetiology. Associations of aetiological groups with the selected criteria were evaluated using correspondence analysis. 424 cancer patients were included: 201 (47%) with bacterial pneumonia, 131 (31%) with opportunistic infections and 92 (22%) with noninfectious disorders. Mechanical ventilation (both invasive and noninvasive) was needed in 328 (77%) patients, treatment for shock in 217 (51%) patients and dialysis in 82 (19%) patients. 142 (34%) patients died in the ICU. Correspondence plots showed that bacterial pneumonia was associated with neutropenia, solid tumour, multiple myeloma, <3 days since symptom onset, shock, unilateral crackles and unilateral radiographic pattern. Opportunistic infections were associated with steroids, lymphoproliferative disorders and haematopoietic stem-cell transplantation, whereas noninfectious disorders were associated with acute leukaemia The selected criteria are strongly associated with causes of ARF in cancer patients and could be used to develop an algorithm for selecting first-line diagnostic investigations and empirical treatments.