Serum paraoxonase levels in gastric cancer

Serum paraoxonase (PON) is a calcium-dependent esterase that is known to contribute to the antioxidant protection conferred by high-density lipoprotein (HDL) on low-density lipoprotein (LDL) oxidation. Serum PON activity was shown to be reduced in patients with diseases such as myocardial infarction, diabetes mellitus, etc in comparison to healthy subjects. However, the relation of serum PON levels to cancer is still not known. So, we intended to measure serum PON, HDL, LDL and very low-density lipoprotein (VLDL) levels and to investigate the relation of serum PON to plasma lipoproteins in the patients with gastric cancer.

We measured serum PON, HDL, LDL and VLDL levels in 20 patients with gastric cancer and in 20 age-and gender-matched healthy controls. We investigated the relationship between PON and HDL, PON and LDL, and PON and VLDL.

Serum HDL levels were lower in the patients than in controls (33.10 +/- 7.75 mg/dL, and 47.30 +/- 6.65 mg/dL, respectively) (p<0.0001). Serum VLDL levels were lower in the patients than in controls (21.65 +/- 6.92 mg/dL, and 33.10 +/- 6.09 mg/dL, respectively) (p<0.0001). Serum LDL levels measured in the patients were not significantly different from those of the controls. Serum PON levels were lower in the patients than in controls (67.10 +/- 17.92 U/L, and 87.50 +/- 23.39 U/L, respectively) and there was a positive correlation between serum PON and HDL levels (r: 0.52, p<0.05).

We concluded that the patients with gastric cancer had low serum PON, HDL, and VLDL levels compared to healthy controls. The importance of PON as a predictive risk factor for cancer should be assessed in future studies.