UTILITY OF SERUM FERRITIN AS A PREDICTOR OF COLORECTAL CANCER IN ELDERLY PATIENTS

Abstract

Objective: Ferritin is an indicator of iron deficiency. Colorectal cancer is an important cause of morbidity and mortality in older subjects. The aim of this study was to determine the value of serum ferritin and ferritin-transferrin saturation in the diagnosis of colorectal cancer in older subjects. Material and Methods: 600 older patients who had undergone upper and lower gastrointestinal endoscopic examination were included into the study. Serum iron profile and C-reactive protein were also recorded. Patients were then evaluated by three different ferritin levels according to their iron profiles: method 1: ferritin < 50 µg/L; method 2: ferritin < 100 µg/L; method 3: ferritin+transferrin saturation index. The relationship between existence of colorectal cancer and serum ferritin level was investigated. Results: 528 patients had normal upper and lower endoscopic findings. 72 patients had colorectal carcinoma with normal upper gastrointestinal findings. Method 1 (ferritin<50 µg/L) predicted 58.4% of patients with colorectal carcinoma with a sensitivity and specificity of 63% (95% CI:52-74) and 53% (95% CI: 48-57) respectively. However, sensitivity [91% (95% CI:82-96)] of method 3 was greater than method 1 and 2 with a AUROC value of 70.4%. There was no difference by means of median ferritin levels. Median transferrin saturation index was significantly higher in group I (Normal subjects) compared to patients in group II (Colorectal cancer patients) (17.5 vs 8%, p<0.001). Conclusion: Serum ferritin <50 μg/L and <100 μg/L have rather low diagnostic yield in the decision making of colonscopic examination for colorectal carcinoma. However, ferritin <100 μg/L and TSI <16% values can be more useful in selecting older patients for colonoscopic examination.