A strand of DNA is seen in an undated handout image.[Agencies]

Cancer experts who probed every gene in tumors from two of the hardest-to-treat cancers found that cancer is much more complicated than anyone thought-and say they found why a cure is so unlikely after a tumor has spread.

But they also discovered a potential new way to treat a common and fatal form of brain cancer, and opened the door to finding cancer before it has spread, when it can still be cured surgically, they reported on Thursday in the journal Science.

'Cancer is very complex -- more complex than we had believed. It is not going to be easy to develop therapies,' said Dr. Bert Vogelstein of Johns Hopkins University in Baltimore and the Howard Hughes Medical Institute.

'If you have 100 patients, you have 100 different diseases.'

The findings suggest that popular new targeted therapies such as Novartis's Gleevec may not work broadly, because they affect only one mutated gene, while cancer is caused by dozens.

A better approach would be to find the pathways -- networks of genes -- that control a tumor's uncontrolled growth and spread, they told reporters in a telephone briefing.

The international team sequenced the more than 20,000 genes in cells from 24 patients with advanced pancreatic cancer and from 22 patients with glioblastoma multiforme.

The typical pancreatic tumor had 63 genetic mutations, while the average brain tumor had 60, they found.

(China Daily September 8, 2008)