New blood test for faster cancer diagnosis

04/07/2014

The chances of a cure for cancer depend very much on an early diagnosis. However, previous methods to detect cancer are complex, expensive and sometimes unreliable. A new blood test now gives hope for a faster and cheaper diagnosis.

Blood test detects tumor genome of patients
In the future, a new blood test could help doctors identify and treat cancer, thereby improving diagnosis, therapy control and subsequent monitoring. The new method, developed by US physicians, detects minute fragments of tumor DNA (ctDNA) circulating in the blood. The cost-effective method identified non-small cell lung carcinoma (NSCLC), the most common form of lung cancer, as the tumorigenic genome in the blood of all advanced-stage patients and every second in the early stages. This reported the scientists to Maximilian Diehn of Stanford University (US state of California) in the journal „Nature Medicine“.

Previous methods are expensive and unreliable
For the diagnosis and therapy control cancer physicians use so far elaborate and partly invasive investigations. So far, analyzes of blood samples for tumor DNA have the problem that they are very expensive and unreliable because they only look for common mutations. The background to this is that dying tumor cells release tiny fragments of the genetic material into the blood. The CAPP-Seq (Cancer Personalized Profiling by Deep Sequencing) method, which has now been developed in the USA, recognizes a large number of conspicuous mutations. „The vast majority of circulating DNA comes from normal cells, even in patients with advanced cancer“, explained co-author Scott Bratman. „We needed a comprehensive strategy to isolate the circulating DNA from the blood and detect the rare cancerous mutations. To increase the sensitivity, we optimized the techniques for extracting, processing, and analyzing the DNA.“ They used cancer database mutations that are typical of NSCLC.

High hit rate and hardly any erroneous cancer findings
The test detected tumor DNA in 100 percent of NSCLC patients from stage II and in 50 percent of stage I patients. In addition, the method not only reached a high hit rate, but also delivered hardly any erroneous cancer findings. Furthermore, the amount of ctDNA provided information about the size of the tumor and also about its development during therapy, in some cases even better than biopsies. As the scientists wrote, the procedure could also be applied to other types of tumors such as the breast, prostate or intestine, if one knows the typical mutation pattern. It is due to the low cost and high reliability for everyday clinical use, both for diagnosis and therapy control, as well as for the subsequent monitoring of patients.

German cancer expert keeps new approach „extremely interesting“
The new approach is also used by Professor Christof von Kalle of the German Cancer Research Center (DKFZ) in Heidelberg, as „extremely interesting“ estimated. On the one hand, it avoids many problems of previous methods and, on the other, links a broad spectrum of tumor-associated mutations with clever evaluation software. However, in the study of non-small cell lung cancer in the early stages probably still exist „air upward“, because there was the hit rate only at 50 percent.

Test works without taking a tissue sample
German scientists also recently announced that they had found a new blood test for early cancer diagnosis. Researchers at the University Hospital Tübingen, the German Cancer Research Center (DKFZ) in Heidelberg, and the Clemenshospital at the University of Münster have said that the new test for oral cancer, prostate cancer and breast cancer will enable early detection of cancer. Like the scientists in the trade magazine „BMC Cancer“ wrote, use the novel blood test that „Immune system and the activity of circulating in the blood Fresszellen that absorb tumor cells“, to identify possibly existing cancers. An important step has been taken on the way to a test that can identify cancer diseases safely and early and does without the removal of a tissue sample. (Sb)