Urinary VOCs and Prostate Cancer: A Modest but Honest Signal

The standard prostate cancer screen, the PSA blood test, is useful but imperfect. This 2015 study asked whether volatile compounds in urine could add diagnostic value on top of it.

What the researchers did

The team analysed urine from 102 men — 59 with prostate cancer and 43 cancer-free, all referred for elevated PSA or an abnormal exam. They extracted the volatile organic compounds (VOCs) from the air above each urine sample and identified them with gas chromatography–mass spectrometry, a laboratory method that separates and names individual molecules. A total of 197 compounds were detected. Machine-learning classifiers were then trained to tell the groups apart.

What they found

• Four compounds carried most of the discriminating signal. Three (an alcohol and two ketones) were lower in cancer; one, pentanal, was elevated. Pentanal is an aldehyde produced by lipid peroxidation — a sign of oxidative stress.
• The best result combined PSA with these four VOCs, reaching about 74% accuracy — better than PSA alone (around 62–64%), but only modestly so.
• Notably, “absence of a signal” can itself be informative: several compounds were down-regulated in disease.

Why it matters

Two things stand out for gut-health science. First, urine is a genuinely rich chemical matrix — nearly 200 compounds were measured — and it carries markers of oxidative stress and metabolic state, not just cancer. Second, the study is refreshingly honest about limits: urine VOCs alone are not a sufficient cancer diagnostic. That distinction matters. This is published research into disease markers, not a consumer test, and the more general takeaway is simply that urinary volatile chemistry reflects systemic metabolic processes.

“Combining PSA levels with urinary VOCs resulted in a marginal improvement in test performance.”