The metabolomics-based diagnostic assay allows early cancer detection. The assay consists of screening for the acetylated form of a drug (Amantadine) given to patients prior to measurement via LC MS in body fluids. This acetylation is performed by the enzyme, Spermine/Spermidine N-Acetyl Transferase (SSAT). It has been documented that elevated levels of SSAT are observed in many cancers including lung, breast, prostate, melanoma and GI cancers. Clinical trials on both cancer and healthy subjects provided proof of principle. In addition, analysis of SSAT mRNA levels in tissue samples allows determination of cancer type.