Diagnostic value of the copper/zinc ratio in digestive cancer: a case control study

The aim of this study was to assess the accuracy of the copper/zinc ratio (Cu/Zn ratio) in the evaluation of a large group of patients with digestive cancer compared to gender and age-matched control subjects. A total of 282 patients was studied and separated into three groups: group I (n = 75), patients with digestive cancer, group II (n = 112), patients with benign digestive disease, and group III (n = 95), healthy subjects. Serum levels of copper and zinc were measured by atomic absorption spectrophotometry. The results showed that the serum levels of copper (mg/dL) in patients with digestive cancer (91.6 +/- 27.3, p < 0.05) were significantly higher than in patients with benign digestive disease (75.8 +/- 19.8) or healthy subjects (54.4 +/- 8.9) and the serum levels of zinc (mg/dl) were significantly lower (68.7 +/- 21.9, p < 0.05) compared to benign digestive disease patients (80.1 +/- 18.7) or healthy subjects (100 +/- 11.4 mg/dl). The Cu/Zn ratio was also significantly higher in patients with digestive cancer (1.45 +/- .58, p < 0.05) than those with benign digestive disease (0.95 +/- 0.28) or healthy subjects (0.55 +/- 0.13). Considering a cutoff value of 0.87, the sensitivity of the copper/zinc ratio was 82.2%, with a specificity of 65.7%, a positive predictive value of 45.8% and a negative predictive value of 91.3%. In conclusion, Cu/Zn ratio was found to be considerably higher in patients with digestive cancer compared to age- and gender-matched controls, with a sensitivity of 82.2% that might be useful in the evaluation of suspected malignancy.