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Pancreatic cancer: The first cells mutate 20 years before the onset of the cancer.
(10/28/2010) Before pancreatic cancer breaks out, it often lurks in the body for years. Scientists from the Howard Hughes Medical Institute and Johns Hopkins University have published their research results in the current issue of the journal "Nature", which assume that pancreatic cancer would be detectable and treatable early on in a large number of cases.
Pancreatic cancer mostly fatal
Pancreatic cancer (pancreatic cancer) leads to death in about 95 percent of those affected. One of the causes is that only 10 to 15% of pancreatic carcinomas can still be treated surgically at the time of diagnosis. In addition, according to recent studies, the five-year survival rate is only between three and 25 percent even after surgery. The chances of survival are correspondingly poorer for inoperable tumors.
Genetic analysis shows that tumors develop over years
In the genetic analysis of pancreatic cancer tumors, the scientists came to the conclusion that the first cell mutations often take place 20 years before the pancreatic carcinoma actually occurs. According to the researchers, it is not surprising that the survival rate in pancreatic cancer e.g. in the UK has not improved over the past 40 years, according to the BBC, because the disease is often aggressive at diagnosis and no longer responds to treatment. As part of the genetic analysis, the researchers examined tissue samples from primary tumors in the pancreas and other areas of the body (metastases) in detail. The DNA of each gene in the tumors was sequenced and signs of mutations were sought. The researchers found that the metastatic tumors had an average of 61 cancer-related mutations, whereby two thirds of the mutations could also be detected directly in the tumor of the pancreas.
Molecular clock to determine the development time
Since the genetic mutations run at a relatively uniform rate, the number of mutations provides an indication of how long the pancreatic carcinomas have developed in the individual stages of the disease. Taking this so-called molecular clock into account, the scientists came to the conclusion that the tumor cells are only formed on average 11.7 years after a single genetic mutation in a cell of the pancreas. It would then take an average of another 6.8 years for the corresponding metastases to develop. However, after metastasis formation, the patients only had less than three years until death. According to the scientists, it can be assumed that the pancreatic carcinomas have developed in the body on average more than 20 years before the fatal cancer broke out.
Earlier diagnosis could help
So far, according to scientist Bert Vogelstein, there have been two theories as to why pancreatic tumors were fatal in around 95 percent of cases. One part of the experts assumed that the pancreatic cancer tumors were very aggressive right from the start, the other part was the assumption that the disease was already very advanced at the time of diagnosis and treatment was therefore impossible or rather hopeless. The results now published in "Nature" make it clear that the second theory seems to apply to at least a large part of the tumors. However, this also means hope for those affected, because with a corresponding early diagnosis, entirely new treatment options could arise and the mostly fatal course of pancreatic carcinoma could be avoided. Across Germany, around 12,800 people develop pancreatic cancer each year, with the average age of men being 68 years old and that of women 75 years old. (fp)
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