Objective: We aimed to investigate factors affecting the prognosis of cancer patients in an intensive care unit and provide guidelines for the admission and follow-up processes. Design: Retrospective study Setting: Health Sciences University, Kartal Dr Lutfi Kirdar Training and Research Hospital, Istanbul, Turkey Subjects: In total, 965 patients admitted to the general intensive care unit during a one-year period from July 2017 to July 2018 were studied. Intervention: Cancer patients Main outcome measure: Age, sex, malignancy type, comorbidities, presence of metastasis and surgeries, reason for intensive care unit admission, length of stay, hospital unit referring the patient to the intensive care unit, mechanical ventilator, inotropic drug administered, hemofiltration requirements, resuscitation history and survival rates were recorded. Results: We observed significantly lower survival rates among patients who were diagnosed with breast or hematological cancer; who had comorbid conditions or metastases; who underwent surgeries; who were admitted to the intensive care unit due to septic shock, cerebral infarction, cardiopulmonary resuscitation, or multiple organ failure; who were on mechanical ventilation; who had been treated with hemofiltration; or who had received inotropic support. However, multivariate analysis showed that presence of comorbid diseases, presence of metastases, admission to the intensive care unit and inotropic support were the only independent factors that negatively affected patient survival. Conclusions: Patients with cancer having high risk of mortality may be provided hospice or palliative intensive care instead of admission to the limited number of general intensive care units.