Stomach cancer is notoriously difficult to diagnose effectively, but a new study used a simple and accurate test of "bad" breath that can detect the existence and extent of the illness right away.

The research, published in the British Journal of Cancer by Israeli and Chinese scientists, shows a 90% accuracy rate in distinguishing stomach cancer from other stomach complaints in 130 patients, and in judging how far the cancer has progressed.

The breath test uses a nanomaterial sensor to analyze the chemicals released in exhaled air. Unique chemical "bad" breath signatures can indicate the development of stomach cancer.

This is remarkably simpler and more convenient than endoscopy, the existing method of detecting stomach cancer.

Endoscopy requires a specialist to stick a long, flexible tube with a small camera attached at the end down the throat and into the digestive system of a sedated patient.  If any abnormal tissue is seen, it can be removed in a biopsy through the endoscope and analyzed by a lab.

The new breath test, on the other hand, is noninvasive and can be used by a general practitioner during a routine check-up to rule out cancer.

If approved for general use, the stomach cancer breath test can make an enormous difference in the healthcare of people in regions without access to extensive medical care and tools like endoscopy.

The breath test was developed by a team led by Dr. Hossam Haick of Technion-Israel Institute of Technology, based on a growing body of research investigating the use of chemical breath signatures to detect different types of cancer.

The breath test sensor contains microscopic nanomaterials that can find just a few biomarker particles floating in exhaled air, using a method called "discriminant factor analysis (DFA) pattern recognition."

Chemical pattern detection in the exhaled air is fine enough to cancel out the effects of factors like recently eaten foods and alcohol and tobacco use.

"The promising findings from this early study suggest that using a breath test to diagnose stomach cancers, as well as more benign complaints, could be a future alternative to endoscopies - which can be costly and time-consuming, as well as unpleasant to the patient," said Dr. Haick in a statement.

The research shows that cancerous growths in the body release volatile organic compounds, which can be detected using the right methods.

The compounds don't cause bad breath that is noticeable to the average human nose, but a German study from 2010 showed that dogs could pick up the scent and be trained to detect cancer.

In the sample of 130 patients complaining of stomach ailments, 37 patients had stomach cancer, 32 had stomach ulcers, and 61 had other complaints.

The breath test also indicated the difference between early and late-stage stomach cancers - which could make a huge difference in catching stomach cancer early enough to treat it effectively.

"Only one in five people are able to have surgery as part of their treatment as most stomach cancers are diagnosed at stages that are too advanced for surgery," said Kate Law, director of clinical research at Cancer Research UK, to BBC News.

"Any test that could help diagnose stomach cancers earlier would make a difference to patients' long-term survival."

Stomach cancer is usually diagnosed far too late for effective treatment, since early symptoms like indigestion, heartburn, and stomachache are similar enough to those of many other benign medical conditions that endoscopies are not deemed necessary until more serious symptoms are present.

In advanced stages of stomach cancer, patients lose weight and appetite, and develop bloody and black stools. At that point, it can be too late for surgery or effective treatment.

The five-year survival rate of stomach cancer is only about 28%, according to the American Cancer Society, since most stomach cancers are found too late for treatment.

About 21,600 Americans are estimated to be diagnosed in 2013, with half of them eventually dying from the cancer's progression. Stomach cancer is far more common in developing parts of the world without extensive medical care, and is a leading cause of cancer-related deaths internationally.

The research team is currently running a larger study to validate the breath test and confirm that it can eventually be used in general medical care in order to diagnose and treat stomach cancer in its early stages.