Detecting and monitoring breast cancer may one day be performed through a simple blood test, a new study suggests, showing that measuring naturally occurring carbon and nitrogen isotopes can help to reveal the presence of cancer cells.
The study, “13C and 15N natural isotope abundance reflects breast cancer cell metabolism,” published in Scientific Reports, was developed at The Australian National University.
“A blood test for breast cancer is several years away from being used in hospitals, but we think we have discovered a new way of detecting breast cancer in the first instance as well as ongoing monitoring,” Guillaume Tcherkez, a professor and ARC Future Fellow at the ANU Research School of Biology.
Chemical elements like carbon and nitrogen can differ in their neutron number, generating what is called isotopes. Although carbon-12 (12C) carbon and nitrogen-14 (14N) are the most common isotopes, 13C and 15N can also be found in living organisms as byproducts of their metabolism.
Several medical applications of these stable isotopes currently exist, like the 13C-urea breath assay used to detect ulcers. Changes in metabolism, like those that occur in cancer, may cause enzymes to use more of a rare isotope instead of a common isotope, leading to changes in their natural abundance that can be easily assessed.
To address whether the metabolic alterations known to occur in breast cancer could be changing the ratio of such isotopes, the researchers tested intact breast cancer biopsies and cultured breast cancer cell lines.
“Our research shows the presence of isotopes carbon-13 and nitrogen-15 in certain proportions in a tissue sample can reveal whether the tissue is healthy or cancerous,” Dr. Illa Tea, with The John Curtin School of Medical Research at ANU and the CEISAM laboratory at the University of Nantes, said in a press release.
Indeed, the researchers found that natural 13C and 15N abundance could discriminate normal from cancerous biopsies; cancer biopsied had a 4% increase in 13C and were depleted of 15N. Similar results were obtained in cultured cell lines, which allowed the researchers to exclude effects from confounding factors like patient age or pharmacological treatments.
They also found that these isotope differences were caused by a differential utilization of carbon and nitrogen isotopes in metabolites of the urea cycle in the liver, which can be analyzed in the blood of cancer patients.
“We could develop clinical applications from this research to detect a change in the isotopic proportions in compounds present in blood, that may indicate the presence of cancer,” Tea said.
The researchers noted that since other cancer types also display changes in their metabolism, this test may be applicable to detecting breast and other cancers.