This study aims to investigate whether Mean Platelet Volume (MPV) and other blood count parameters measured at admission can predict mortality in cancer patients admitted to the intensive care unit (ICU). Patients with cancer are highly vulnerable to complications and organ failure, making early risk assessment vital for improving treatment strategies. Researchers will retrospectively review the medical charts and electronic health records of adult patients who stayed in the anesthesia ICU for longer than 24 hours between 2020 and 2025. No new laboratory tests, interventions, or patient contact will occur. The collected data will be analyzed to determine the relationship between initial MPV levels and patient survival outcomes.

This retrospective, observational, single-center study will evaluate the predictive value of initial Mean Platelet Volume (MPV) and other hemogram parameters (such as Red Cell Distribution Width [RDW] and platelet count) on intensive care and hospital mortality. The primary objective is to investigate the correlation between these routinely measured, cost-effective biomarkers and survival outcomes in oncological critical care patients. The study hypotheses are structured as follows:

• H0: There is no significant relationship between the admission MPV value and intensive care or hospital mortality in intensive care patients with cancer.
• H1: There is a significant relationship between the admission MPV value and intensive care or hospital mortality in intensive care patients with cancer. Data regarding demographics (age, sex), clinical diagnoses, comorbidities, length of stay, APACHE II, SOFA scores, and laboratory parameters (CRP, procalcitonin) will be extracted from hospital electronic database records. All patient data will be anonymized before statistical analysis.

Note on Study Design: This study is designed as a retrospective cohort study. Due to system registry constraints in the protocol module, the time perspective has been specified as 'Other' (Retrospective Cohort).

Inclusion Criteria:

• Adult patients aged 18 years and older.
• Patients with a pathologically or clinically confirmed diagnosis of cancer (solid or hematological malignancies).
• Patients who were admitted to the Anesthesia Intensive Care Unit (ICU) between 2020 and 2025.
• Patients with an ICU length of stay longer than 24 hours.
• Patients with complete medical records, including baseline complete blood count (CBC) and Mean Platelet Volume (MPV) measured at the time of ICU admission.

Exclusion Criteria:

• Patients under the age of 18.
• Patients who stayed in the intensive care unit for less than 24 hours.
• Patients with missing or incomplete medical charts, laboratory data, or survival status records.
• Patients who were readmitted to the ICU during the same hospital stay (only the first admission will be evaluated).
• Patients who received massive blood or platelet transfusions immediately prior to the baseline laboratory measurement, which could artificially alter platelet parameters.

The study population consists of adult oncological patients who required critical care and were admitted to the anesthesia intensive care unit of a tertiary oncology training and research hospital between 2020 and 2025.

Individual participant data will not be shared globally to maintain patient confidentiality and privacy in accordance with local data protection regulations and institutional review board restrictions. However, the coded datasets and statistical analyses used during the current study may be available from the corresponding author upon reasonable academic request.