The investigators have determined that the drug amantadine hydrochloride is metabolized by acetylation by a specific enzyme named spermidine/spermine N-acetyltransferase (SSAT). This enzyme is increased in cancer cells. The investigators hypothesized that the amount of N-acetylamantadine excreted in urine during the first 12 hours after an oral dose would serve as a diagnostic biomarker for the presence of cancer in a human test subject.