Bladder cancer detected via amplified gene in urine cells

October 9, 2008

Counting the copies of a specific gene in cells gathered from a urine sample may provide a simple, noninvasive way to detect bladder cancer, according to researchers at The University of Texas M.D. Anderson Cancer Center in Houston.

Counting the copies of a specific gene in cells gathered from a urine sample may provide a simple, noninvasive way to detect bladder cancer, according to researchers at The University of Texas M.D. Anderson Cancer Center in Houston.

When the telltale gene, Aurora kinase A (AURKA), is numerous and overexpressed in urothelial cells, errors during cell division follow, the team reported (J Natl Cancer Inst 2008; 100:1401-11). The new cells have too few or too many chromosomes.

“Abnormal chromosome counts are the most fundamental feature—the signature—of human cancers,” said senior author Bogdan Czerniak, MD, PhD. “We have further clarified the role that the Aurora kinase A gene plays in this misaggregation of chromosomes in bladder cancer. As a biomarker, Aurora kinase A can detect bladder cancer in voided urine with high degrees of sensitivity and specificity.”

The team used fluorescence in situ hybridization (FISH) to count copies of the gene in urothelial cells from the bladder culled from urine samples. A blinded analysis of samples from 23 bladder cancer patients and seven cancer-free controls showed the AURKA biomarker identified all 23 cancer cases and correctly characterized six of the seven controls as not having bladder cancer.

The biomarker test was validated in urine samples from a separate group of 100 bladder cancer patients and 148 controls. Blinded analysis showed the biomarker accurately identified 87 of the cancer cases and characterized 96.6% of the controls as cancer-free, producing only five false positives.

Cytologic analysis was conducted on additional samples from 59 of the cancer cases. Microscopic examination of the cells identified 48 of the 59 cancers (81.4%). Nine of the 11 cases mischaracterized by cytology were correctly identified by the FISH AURKA test.

“Our next step is to develop a U.S. FDA-approved, commercially available test,” Dr. Czerniak said. “That will require independent validation in prospective, multi-institutional clinical trials.”