• E-mail
• Print
• Comment
• Font Size
• Digg
• del.icio.us
• Discuss article

Experts Say Cancer More Complicated Than Previously Believed

Posted on: Friday, 5 September 2008, 10:01 CDT

An international team of cancer experts reported Thursday that cancer is much more complicated than previously believed, and have discovered why curing the disease is so difficult once a tumor has spread.

The scientists reached their conclusion after examining every gene in tumors from two of the most difficult-to-treat cancers.

However, the researchers said they had found a potential new method to treat a common but fatal form of brain cancer, and also may have identified a way to detect cancer before it has spread, while it can still be surgically cured.

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

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

The findings also indicate that the newer targeted therapies, such as Novartis' Gleevec, may not be broadly effective since they affect only one mutated gene, while cancer is caused by many.

A better approach, the experts said, would be to track down the networks of genes that control a tumor's uncontrolled growth and spread.

In conducting their research, the scientists sequenced more than 20,000 genes in cells from 22 patients with glioblastoma multiforme, the most common type of brain tumor that typically kills patients within a year, and 24 patients with advanced pancreatic cancer. The typical pancreatic tumor had 63 genetic mutations, while the average brain tumor had 60, the team discovered.

However, only a dozen pathways were abnormal in most of the tumors, some of which were in expected areas, such as the regulation of programmed cell suicide, also known as apoptosis, the process by which abnormal cells self-destruct.

"Often what appeared to be mutations in disparate genes turned out to be working in common pathways," Dr. Kenneth Kinzler of Johns Hopkins, who participated in the research, told Reuters.

One unexpected finding was a new gene called IDH1 found in glioblastoma multiforme, the type of brain tumor Senator Edward Kennedy was diagnosed with in May, said Dr. Victor Velculescu of John Hopkins University.

Patients in the study with these mutations were younger and lived longer than the average brain tumor patient.

"Glioblastoma multiformes used to be thought of as one disease. It is now clear they are two," Velculescu said during a briefing with reporters.

Vogelstein said the findings suggest that pharmaceutical companies should change their approach in developing new drugs to treat cancer.

While drugs such as Gleevec, a pill, revolutionized the treatment of a type of blood cancer called chronic myeloid leukemia (CML), "our work suggests that most solid tumors are really nothing like CML," Vogelstein added.

"It is extremely unlikely that drugs which target a single gene like Gleevec will be active against a major fraction of solid tumors. Instead of screening for drugs against single proteins, our work suggests that it may be more productive to screen for drugs that act against core pathways," he said.

The research also suggests better methods to screen for cancers, Vogelstein said.

"Our group as well as others have found that you can detect mutations outside of cells, just floating in the plasma, in virtually all patients with advanced colorectal cancer and about two-thirds of those with relatively early tumors," he said.

"It will be possible soon to detect them in many other samples from patients, say in their blood, even when the tumors are early. Almost all tumors and even those of the brain and pancreas would be curable if they are caught early."

The study was reported on Thursday in the journal Science. An abstract is available here.

Image Courtesy National Institutes of Health

Source: redOrbit Staff & Wire Reports

More News in this Category