Researchers have developed a non-invasive, low-cost test that could help doctors diagnose some types of malignant childhood tumors, according to a study published Wednesday by the University of Cambridge.

The target of the test is a type of cancer known as germ cell cancer. Germ cells can develop into tumors, particularly in the testes or ovaries, where the cells are normally found. Occasionally, germ cells can become trapped in the wrong part of the body during development and may later turn into brain tumors, for example.

Accurate diagnosis and monitoring is crucial to improving outcomes for patients. But all of the current tests are expensive, and none are ideal, the study said.

Researchers at the University of Cambridge and Addenbrooke's Hospital have developed a test for blood and cerebrospinal fluid samples that looks for a specific panel of four pieces of short genetic code known as microRNAs, which are found in greater quantities in malignant germ cell tumors.

The test can distinguish malignant germ cell tumors from benign germ cell tumors and other cancers, and can be used for diagnosis of malignant germ cell tumors in any part of the body, including the brain, according to the study.

The test can also be used to check the effectiveness of treatments and, as it is safe and cost-effective, allows for frequent testing to monitor for the recurrence of malignant germ cell tumors, researchers said.

"At the moment, we are not good enough at diagnosing these tumors and monitoring their treatment: we need better, safer and more cost-effective tests," said Professor Nick Coleman from the University of Cambridge.