As with other cancers, an early diagnosis of kidney cancer can result in curative treatment whereas the prognosis for advanced kidney cancer is poor. The challenge in diagnosing cancer early is developing an inexpensive, noninvasive, accurate and simple screening test. A urine test meets these standards.
"We used a common laboratory procedure to test the urine of 50 patients with kidney cancer," explained Fox Chase molecular biologist Paul Cairns, Ph.D. "Forty-four of the 50 tests showed gene changes in the urine that were identical to the gene changes found in the tumor tissue taken at the time of surgery."
When the same test was conducted on the controls - urine from people without cancer - none showed the relevant gene alterations that were found in the urine from people with cancer.
"The test appears to be remarkably accurate with no false-positives in this study," said Robert G. Uzzo, M.D., a urologic surgeon at Fox Chase and lead author of the abstract. "In addition, one of the most impressive outcomes of this research is that the test also identified 27 of the 30 patients with stage I disease."
The researchers then tested the urine of 17 patients after they had surgery to remove the cancerous kidney. Mutated genes present in the urine prior to the kidney removal were not present in the urine after the kidney was removed.
"This step in our research further supports the accuracy of this potential screening test but also demonstrates the possibility of using urine to monitor the patient after treatment," Uzzo added.
The researchers used a molecular DNA-based test called methylation-specific PCR (polymerase chain reaction) to detect gene alterations that initiate and fuel the onset of cancer. The test searched for six cancer specific tumor-suppressor genes that were altered - causing them to falter in their critical role of preventing errant cell growth. These six genes are usually identified only after a pathologist's review of tumor tissue.
"In addition to early detection, differential diagnosis and surveillance, this testing could potentially be extended in the future to simultaneously provide molecular staging and prognostic information," Uzzo concluded.
Currently, kidney cancer is diagnosed after radiographic imaging of the kidney, which may include an ultrasound, CT scan and/or MRI. Biopsy of a kidney mass is often difficult to interpret or may give a false negative result and therefore currently confirmation of radiographic results is primarily after surgical excision. There is no protein marker test for kidney cancer as there is for prostate cancer with the PSA test.
This research was supported in part by a grant from the Flight Attendants Medical Research Institute (FAMRI) and the National Cancer Institute's Early Detection Research Network.
Fox Chase Cancer Center was founded in 1904 in Philadelphia, Pa. as the nation's first cancer hospital. In 1974, Fox Chase became one of the first institutions designated as a National Cancer Institute Comprehensive Cancer Center. Fox Chase conducts basic, clinical, population and translational research; programs of prevention, detection and treatment of cancer; and community outreach. For more information about Fox Chase activities, visit the Center's web site at http://www.