Acute Kidney Injury in Hospitalized Cancer Patients: Single-Centre Real-Life Analysis of Incidence and Clinical Impact

Background: Acute kidney injury (AKI) is a frequent and clinically relevant complication in cancer patients, with highly variable incidence. AKI increases morbidity and mortality, prolongs hospitalization, and may limit access to oncologic therapies. This study evaluated the incidence, risk factors, and outcomes of AKI in hospitalized cancer patients. Methods: We retrospectively analyzed patients admitted between 1 January 2016 and 31 December 2019. Individuals with cancer were identified and categorized into three groups: hematologic malignancies, solid cancers with metastases, and solid cancers without metastases. Demographic, clinical, and laboratory data were collected, and AKI was defined and staged according to KDIGO criteria, evaluating serum creatinine changes. Results: Among 56,390 hospitalized patients, 6723 (11.9%) had a cancer diagnosis. AKI incidence was significantly higher in cancer versus non-cancer patients (30.1% vs. 19.6%). Hematologic cancers showed the highest incidence (39.3%). Among hematologic patients, ICU admission, sepsis, and diabetes were strongly associated with AKI. In non-metastatic solid cancers, more conventional factors—including female sex, older age, sepsis, and ICU admission—were significant predictors. In contrast, in metastatic solid cancers, traditional AKI risk factors did not correlate with increased AKI occurrence. In cancer patients overall, AKI per se did not increase mortality risk; however, stage 3 AKI was associated with significantly higher mortality (HR 1.37, 95% CI 1.13–1.66, p < 0.001). Conclusions: AKI is common in hospitalized cancer patients, with specific patterns and heterogeneous risk factors and impact on outcomes. Implementation of tailored preventive strategies and early recognition are necessary to mitigate progression and improve clinical trajectories.