Early detection of cancer greatly increases the chances for successful treatment. In many cases, the sooner cancer is diagnosed and treated, the better a person's chance for a full recovery. If a person develops cancer, he can improve the chance that it will be detected early if he has regular medical checkups. Often cancer can be found early during a physical exam or with routine tests, even if a person has no symptoms.
Among the existing methods, imaging is frequently used. Images of areas inside the body reveal whether a tumor is present. These images can be made in several ways. In many cases, a special dye is used so that certain organs show up better on film. The dye may be swallowed or put into the body through a needle or a tube. X-rays are the most common way to make images. In radionuclide scanning, the patient swallows or is given an injection of a mildly radioactive substance. A scanner measures radioactivity levels in certain organs. By looking at the amount of radioactivity in the organs, abnormal areas can be found. Ultrasonography is another procedure for viewing the inside of the body. High-frequency sound waves echoes produce sonograms. In MRI, a powerful magnet linked to a computer is used to make detailed pictures of areas in the body. Endoscopy allows to look into the body through a thin, lighted tube called an endoscope. During the exam, tissue or cells for closer examination may be collected.
Although no single test can be used to diagnose cancer, laboratory tests such as blood and urine tests give important information. If cancer is present, the lab work can show the effects of the disease on the body. In some cases, special tests are used to measure the amount of certain substances in the blood, urine, and other body fluids, or tumor tissue. The levels of these substances may become abnormal when certain kinds of cancer are present. The physical exam, imaging, endoscopy, and lab tests can show that something abnormal is present, but a biopsy is the only sure way to know whether the problem is cancer. In a biopsy, a sample of tissue is removed from the abnormal area and examined. The pathologist can usually tell what kind of cancer it is and may be able to judge whether the cells are likely to grow slowly or quickly.
Those tests and screenings are rather invasive, are not so simple to do and are not without risks. This is a major barrier for persons to do preventive screening or tests, so often those tests are realized in an rather advanced stage of the cancer. Breathing into a machine to deliver a breath sample for early detection of lung cancer is a routine test that is non invasive, safe and simple to do, so likely to be a preventive screening test voluntarily accepted by the patients and will be a mean to detect lung cancer in a very early stage.
There is strong evidence that particulate cancers can also be detected by molecular analysis of exhaled air, even in very early stages of the disease. Breath analysis represents a new non-invasive diagnostic, which can provide information beyond conventional analysis of blood and urine. Exhaled air can be sampled as often as necessary without any restriction. It may even be done for newborn babies, or patients at the intensive care unit. The EU project BAMOD was focused onto the diagnosis of minimal disease and early stages of lung and esophageal cancer. Based on its competence, the project had the expertise to investigate and screen for hundreds of molecules in the exhaled breath and the statistical tools to identify specific cancer markers.
A study of the BAMOD project covered the release of volatile organic compounds (VOCs) from the lung cancer cell line CALU-1 in vitro. [Wojciech et al.; Cancer Cell International 8: 17.] The aim of this work was to confirm the existence of volatile organic compounds (VOCs) specifically released or consumed by lung cancer cells. The findings demonstrate that certain volatile compounds can be cancer-cell derived and thus indicative of the presence of a tumor, whereas other compounds are not released but seem to be consumed by CALU-1 cells.
This work is a first step to get a better understanding on the metabolism of VOCs from cancer cells. Through these investigations researchers received some hints on which substances are candidates for biomarkers of cancer disease and thus may finally provide a technically feasible method for early and non-invasive diagnosis of lung cancer. However, biochemical background of all discussed compounds should be elucidated before using them as fully assured biomarkers. Origin, biochemical pathways and distribution of the most volatile organic marker molecules are still unknown. For the use of breath tests in clinical praxis it is essential to know also origins of marker molecules as well as potential confounding variables, but these results are already a step in the right direction!