May 20, 1998
Johns Hopkins researchers have developed a new test that may allow doctors to regularly and quickly check for early cancers in patients at risk for developing cancer due to genetic or environmental factors.
The test temporarily slows DNA production in cancer cells, causing some elements of DNA to accumulate in the blood. When these materials are excreted in large amounts in urine, they indicate the presence of cancer.
Hopkins researchers found 8 of 11 cancer patients tested positive for cancer using the new technique. The patients, who were diagnosed with cancer before taking the new test, had a variety of tumors. The results of the study, supported in part by an American Society of Clinical Oncology Young Investigator Award and by the National Institute of Child Health and Human Development, appear in the May issue of In Vivo.
Scientists say initial results are promising but the test must be validated by additional research.
"We must study larger groups of patients, and if these preliminary results are confirmed, doctors possibly could use the test for the early detection of tumors in patients at risk for cancer," says Saul Brusilow, M.D., professor of pediatrics. "It might also be useful as a post-surgical test for residual cancer cells."
For the test, patients gave a baseline urine sample and took one allopurinol pill. This drug, ordinarily used to treat gout, also temporarily interferes with the production of elements of DNA called pyrimidines. Patients' urine was then collected in four periods over the next 24 hours and tested for increased levels of orotidine and orotate, two compounds used to build pyrimidines.
Increases in the levels of these compounds were surprisingly large.
"These dramatic changes suggest that it may be possible to use the test to detect some small tumors earlier than we ever could before," says Brusilow.
If the test's sensitivity is confirmed, Brusilow believes it may be possible to adapt it for administration through bacterial inhibition assays, an inexpensive technique commonly used to screen newborn babies for phenylketonuria and other diseases.
"We're still relatively early in the development, but I'm confident that the test can be implemented in a cost-effective manner," says Brusilow.
Other authors were Michael Carducci, M.D., assistant professor of oncology; Michael Choti, M.D., division of surgical oncology; and Nancy Maestri, Ph.D., assistant professor of pediatrics.