S-adenosylmethionine as a biomarker for the early detection of lung cancer

Abstract

Background: S-Adenosylmethionine (AdoMet) is a major methyl donor for transmethylation reactions and propylamine donor for the biosynthesis of polyamines in biological systems, and therefore may play a role in lung cancer development. We hypothesized that AdoMet levels were elevated in patients with lung cancer and may prove useful as a biomarker for early lung cancer.

Methods: High-performance liquid chromatography was used to analyze plasma AdoMet levels in triplicate samples from 68 patients. This included 13 patients with lung cancer, 33 smokers with benign lung disease, and 22 healthy nonsmokers. The three groups of subjects were compared with respect to the distribution of demographic and disease characteristics and AdoMet levels. Distributions were examined using summary statistics and box plots, and nonparametric analysis of variance procedures.

Results: Serum AdoMet levels were elevated in patients with lung cancer as compared to smokers with benign lung disorders and healthy nonsmokers. There were no significant correlations between AdoMet levels and tumor cell types, nodule size, or other demographic variables.

Conclusions: Our data demonstrate that plasma levels of AdoMet are significantly elevated in patients with lung cancer. Plasma AdoMet levels may prove to be a useful tool for the diagnosis of early lung cancer, in combination with chest CT. Registered at: clinicaltrials.gov (NCT00301119).

Figure 1

Box plot of AdoMet level by study group. The median for each data set is indicated by the center line, and the mean is represented by the plus sign. The first and third quartiles are the edges of the square area, which is known as the interquartile range. The extreme values (within 1.5 times the interquartile range from the upper or lower quartile) are the ends of the lines extending from the interquartile range.

Figure 2

ROC curves for cancer compared with high-risk smokers. Top, A: based on AdoMet levels and nodule size jointly. Center, B: based on AdoMet levels alone. Bottom, C: based on nodule size alone.