This study aims to evaluate the ability of G8, CARG, and Frailty scales to predict chemotherapy-related toxicity and the need for G-CSF in elderly cancer patients. It also investigates their correlation with nutritional biomarkers (albumin, prealbumin, hemoglobin, CRP) and the Mini Nutritional Assessment (MNA) test.

Background: Aging is associated with decreased physiological reserves, making elderly cancer patients more vulnerable to chemotherapy toxicity (CT). Traditional performance scales like ECOG may be insufficient for treatment decisions. Tools such as G8, Clinical Frailty Scale (CFS), and the Cancer and Aging Research Group (CARG) score are practical screening instruments recommended by ASCO and SIOG, yet their combined predictive accuracy for CT and granulocyte colony-stimulating factor (G-CSF) usage remains underexplored.

Objectives: This prospective study aims to evaluate the predictive performance of the G8, CARG, and Frailty scales-alone and in combination with nutritional biomarkers (albumin, prealbumin, hemoglobin, CRP)-in forecasting chemotherapy-related toxicity and G-CSF need. It also investigates the correlation between these geriatric assessment tools and Mini Nutritional Assessment (MNA) scores.

Methods: The study will be conducted at Çanakkale University Medical Faculty Oncology Outpatient Clinic. Patients aged 65 and above with a planned chemotherapy regimen will be recruited. Before the first chemotherapy cycle, patients will undergo G8, CARG, Frailty, and MNA assessments. Nutritional biomarkers will be extracted from pre-treatment routine lab tests. Chemotherapy toxicity and G-CSF requirement will be monitored across treatment cycles. ROC, correlation, and regression analyses will be conducted to evaluate predictive validity.

Inclusion Criteria:

• Age ≥ 65 years
• Diagnosed with solid tumor malignancy
• Planned to undergo at least two cycles of adjuvant, neoadjuvant, or metastatic chemotherapy
• Clinically stable condition
• Provided written informed consent

Exclusion Criteria:

• Presence of hematological malignancies
• Concurrent hormonal therapy, targeted therapy, immunotherapy, or radiotherapy
• Acute infection or advanced organ failure (cardiac, hepatic, renal)
• Cognitive or psychiatric impairment preventing test participation
• Prior treatment with G-CSF

The study group consists of cancer patients aged 65 and older who are scheduled to receive at least two cycles of chemotherapy. Patients with hematological malignancies or receiving concurrent targeted, hormonal, immunotherapy, or radiotherapy are excluded.