"Tumor cells are released into stool from the surface of precancers and early-stage colon cancers, but detecting a cancer-initiating genetic mutation among a large quantity of normal DNA from a patient's stool is like looking for a needle in a haystack," said Bettina Scholtka, Ph.D., assistant professor in the Department of Nutritional Toxicology at the University of Potsdam in Nuthetal, Germany.
"By combining for the first time locked nucleic acid-based, wild-type blocking polymerase chain reaction and high-resolution melting, we were able to achieve the desired sensitivity. The extremely high sensitivity of this technique allows us to find very low amounts of different types of the cancer-initiating mutations in patients' stool samples.
"Colon precancer cells carrying these genetic variations are routinely shed in stool samples, but these cells can be detected in blood only after the cancer has advanced, so stool is better than blood if we are to catch these cancers at a very early stage," she added.
About 60 percent and 40 percent of patients with colorectal cancer have genetic variations in the genes APC and KRAS, respectively. Because these variations are also present in precancers, methods for spotting them can help detect colon cancers early. The new method described in this study can detect a single cancer-specific gene variation among 10,000 times the amount of normal DNA, and is up to 5,000-fold more sensitive than other noninvasive screening methods.
A multicenter study is needed to validate the sensitivity and specificity of this new method in comparison with standard screening methods like colonoscopy, according to Scholtka.
Scholtka and colleagues used 80 human colon tissue samples representing cancers and precancers to detect genetic variations using a combination of two techniques: The first technique — locked nucleic acid (LNA)-based, wild-type blocking (WTB) polymerase chain reaction — suppressed normal DNA present in large quantities in the sample; and the second technique — high-resolution melting (HRM) — enhanced the detection of genetic variations.
The researchers were able to detect APC variations in 41 of the 80 samples. They were also able to detect previously unknown variations in APC. In contrast, the routinely used technique called direct sequencing could detect variations only in 28 samples.
They then analyzed 22 stool samples from patients whose colon tissues had APC variations, and nine stool samples from patients whose colon tissues did not have APC variations, as controls. They were able to detect APC variations in 21 out of 22 samples.
The researchers also detected variations in the KRAS gene using 20 human colon tissue samples to demonstrate that the WTB-HRM method can be used to detect variations in genes other than APC.
"By using our technique for examining a selection of genes that become mutated during the process of colon cancer formation, it is possible to detect the very first stage of colon cancer and even precancers in a stool sample," said Scholtka. "It will be possible to prevent cancer in many cases by removing the precancerous lesions after early detection."
Follow the AACR on Twitter: @AACR
Follow the AACR on Facebook: http://www.facebook.com/aacr.org
About the American Association for Cancer Research
Founded in 1907, the American Association for Cancer Research (AACR) is the world's oldest and largest professional organization dedicated to advancing cancer research and its mission to prevent and cure cancer. AACR membership includes more than 34,000 laboratory, translational, and clinical researchers; population scientists; other health care professionals; and cancer advocates residing in more than 90 countries. The AACR marshals the full spectrum of expertise of the cancer community to accelerate progress in the prevention, biology, diagnosis, and treatment of cancer by annually convening more than 20 conferences and educational workshops, the largest of which is the AACR Annual Meeting with more than 18,000 attendees. In addition, the AACR publishes eight peer-reviewed scientific journals and a magazine for cancer survivors, patients, and their caregivers. The AACR funds meritorious research directly as well as in cooperation with numerous cancer organizations. As the scientific partner of Stand Up To Cancer, the AACR provides expert peer review, grants administration, and scientific oversight of team science and individual grants in cancer research that have the potential for near-term patient benefit. The AACR actively communicates with legislators and policymakers about the value of cancer research and related biomedical science in saving lives from cancer. For more information about the AACR, visit http://www.AACR.org.
To interview Bettina Scholtka, contact the press office of the University of Potsdam at 49-0-331-977-0 or email@example.com. For other inquiries, contact Jeremy Moore at firstname.lastname@example.org or 215-446-7109.
Jeremy Moore | EurekAlert!
Oxygen can wake up dormant bacteria for antibiotic attacks
08.12.2016 | Penn State
NTU scientists build new ultrasound device using 3-D printing technology
07.12.2016 | Nanyang Technological University
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
08.12.2016 | Life Sciences
08.12.2016 | Physics and Astronomy
08.12.2016 | Materials Sciences