Breath test may be able to detect colorectal cancer


A test to determine colon, or colorectal, cancer often involves looking at blood and stool samples for signs, and then further invasive testing if a positive marker is found. On top of that, only a small fraction of those who test positive will actually have colorectal cancer.

Now, a new study published in the British Medical Journal on Dec. 5 shows that a test that used only exhaled breaths from patients was more than 75 percent accurate in finding patients who had the disease.

"The technique of breath sampling is very easy and non-invasive, although the method is still in the early phase of development," Dr. Donato F. Altomare, a researcher with the Department of Emergency and Organ Transplantation at the Universite degli Studi di Bari Aldo Moro in Bari, Italy, said in a press release. "Our study's findings provide further support for the value of breath testing as a screening tool."

There will be an estimated 103,170 colon cancer and 40,290 rectal cancer cases in the U.S. in 2012, according to the National Institutes of Health. About 51,690 people will died from the two cancers this year. It is the second leading cause of cancer deaths in the United States.

Colorectal cancer normally begins as a noncancerous, benign polyp or growth in the glands in the lining of the colon or rectum and progresses to cancerous, malignant tumors. Risks for colon cancer include being older than 60, being of African American or Eastern European descent, having a diet high in red or processed meats and having a family history of colon cancer. Having cancer elsewhere in the body, including a personal history of breast cancer, having colorectal polyps or an inflammatory bowel disease can also increase the risk.

The U.S. Preventive Services Task Force recommends routine screening for colorectal cancer, such as with a colonoscopy, for adults beginning at age 50 until they are 75 years old.

Since cancer tissue metabolizes at a different rate compared to healthy cells, it produces some byproducts called volatile organic compounds (VOCs) that can be detected in a person's breath. Previous studies have used dogs to detect these odors.

Researchers tested the breaths of 37 colorectal patients and 41 healthy others to create a test to find specific VOCs. Then,a probabilistic neural network (PNN) was created to help find the VOCs in question. The test was able to find patients with colorectal cancer in 76 percent of the cases in a test using 19 patients.

Dr. Claire Turner, a lecturer in analytical chemistry at the Open University in Milton Keynes, England, told the BBC that while promising, it's often hard to distinguish between the VOCs and what a person was eating, if they had another illness or if they spent time at a hospital. She was not involved in the study.

"These technologies show a great deal of promise, and hopefully we will see larger studies in the future. However, we are unlikely to see this kind of breath testing available widely in the short term," she said.

Dr. Durado Brooks, director of prostate and colorectal cancers for the American Cancer Society, also told HealthDay that it was too early to get excited about this test, especially since one of the goals in screening is to look for polyps which aren't detected by the breath test. He too was not involved in the study

"It's an interesting concept, but this is in the very early stages," Brooks said. "There's no way to tell if this would work in the general population."