'Sniff Test' may replace prostate biopsy procedures

Paul Basilio, MDLinx | April 03, 2017

New research has identified the molecules that are likely responsible for the scent of prostate cancer, opening up the possibility of a “sniff test” to replace the sometimes dreaded biopsy procedures in patients with suspected prostate cancer, according to new research that was presented at the 253rd National Meeting & Exposition of the American Chemical Society (ACS).

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Researchers identified a small set of molecules that were present in 90% of the samples from patients with prostate cancer but not in samples from those without.

Prostate cancer is the third most common type of cancer in the United States, and early detection is critical. However, diagnosis is often fraught with challenges.

Current screening tests measure blood levels of prostate-specific antigen (PSA) to determine whether a biopsy specimen of the prostate should be obtained. Elevated PSA levels often have non-cancerous causes, so this test is widely recognized as flawed as it often leads to unneeded procedures.

“Currently, about 60% of men who get a biopsy to test for prostate cancer don’t need one,” according to Amanda Siegel, PhD, one of the study’s authors. “We hope our research will help doctors and patients make better-informed decisions about whether to have a biopsy, and to avoid unwarranted procedures.”

The idea for the study came about after previous research showed that trained dogs could detect prostate cancer with 97% accuracy, according to Mangilal Agarwal, PhD, the project’s principal investigator. His team had already begun work on a sensor that could detect hypoglycemia on a person’s breath, as dogs have also been able to do. After reading about the dogs and prostate cancer, Dr. Agarwal’s lab set out to determine what the dogs were sensing.

“If dogs can smell prostate cancer, we should be able to as well,” said Dr. Siegel.

Drs. Agarwal and Siegel are both associated with the Integrated Nanosystems Development Institute of Indiana University-Purdue University Indianapolis (IUPUI) and the Richard L. Roudebush VA Medical Center.

In this study, the IUPUI and VA team collected urine samples from 100 men undergoing biopsy of the prostate gland. A pre-processing step was added to avoid issues with sample degradation that had plagued previous attempts. Sodium chloride was added, and the pH was neutralized to ensure the samples remain intact for analysis.

Gas chromatography-mass spectrometry was then used to identify the volatile organic compounds (VOCs) in the area above the urine samples. This method allowed researchers to pinpoint a small set of molecules that were present in 90% of the samples from patients with prostate cancer but not in samples from those without.

In the future, the team plans to conduct large-scale testing to validate the findings. A proposal is also in the works to confirm the molecular signature identified during the study and to compare the results to those obtained with trained dogs.

Drs. Siegel and Agarwal say that their test could become available to doctors within the next few years, depending on the outcome of the future projects. Their short-term vision is for samples to be sent to a lab for analysis, but the ultimate goal is a sensor that can be used in the physician’s office.

The Richard L. Roudebush VA Medical Center contributed support and funding for this study.

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