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Joint Israeli-American team closes in on cause of colon cancer

Posted By David Brinn On March 13, 2005 @ 8:00 pm In | No Comments

A closeup of a cancerous colon – it was found that a huge percentage (86.3) of the cancerous tumors in the large intestine contain the DNA of the JC virus.A joint Israeli-American research project could result in a breakthrough in preventing colorectal cancer. Cancer of the large intestine – also known as colon cancer – affects 5% of the world’s population and claims 56,000 Americans each year.

A team led by Dr. C. Richard Boland, chief of gastroenterology at Baylor University Medical Center at Dallas, and Prof. Yaron Niv of the Gastroentrology center of Beilinson Hospital in Petah Tikva, have closed in on a likely agent in colorectal tumor creation – a normally harmless virus named JC, which is present in 70 percent to 80 percent of all humans.

Their findings were published in the January edition of Current Opinion in Gastroenterology .

Their research indicates that the JC virus is a source of chromosomal instability that triggers genetic mutations leading to cancer. It was found that a huge percentage (86.3) of the cancerous tumors in the large intestine contain the DNA of the JC virus.

If Niv and Boland can verify that the JC virus is the culprit, development of a vaccine against it may prevent colorectal cancer.

“We’re talking about an important precedent,” said Niv, also a professor at Tel Aviv University. Today, “the five year survival rate is only about 50%. For that reason, it’s very important to find a solution to this devastating disease,” he told ISRAEL21c.

“The scientific community knows – after more than 20 years of research – the genetic and environmental facts about the polypic carcinoma sequence. But we don’t know the starting point – there’s something missing from the puzzle.”

Niv and Boland studied hundreds of Israeli patients with colon cancer, looking at their cancer tissue for DNA sequences of the JC virus in the cancer cells. They found that more than 80% of those tested – including Ashkenazi and Sephardi Jews, and Arabs – had the DNA for the JC virus.

“We believe that the JC virus – or more specficially – the T-antigen protein that is synthesized by the virus may be the trigger in the development of at least 20-40% of the cases of colorectal cancer,” said Niv.

Niv and Boland have had a close personal and working relationship since they met 25 years ago while they were both fellows at the University of California in San Francisco.

“He was ahead of me by two years or so, but our friendship and professional relationship has strengthened over the years – he became head of GI at Baylor and I became head of GI at Rabin, and we’ve done a lot of research together. Baylor is the leading researcher in the world dealing with genetic changes in colorectal cancer.

Niv spent his sabbatical in Boland’s lab in Dallas, where their current research was conducted.

According to Niv, the JC virus sits in the intestine during childhood, and only after many years of dormancy, an until now unknown trigger begins to change the genetic structure of the large intestine which enables the cancer to develop.

If diagnosed early, chances of full recovery are good, he said. “We’re sort of lucky in that this cancer starts as benign polyps which remain that way for 8-10 years, and if diagnosed can be removed before it can cause any damage.”

In Israel, a major effort is underway to get middle-aged Israelis to be tested annually for pre-cancerous polyps or cancer in the colon/rectum. The Israel Cancer Association (ICA), Clalit Health Services and the other health funds, with encouragement from the Health Ministry, have declared March Colon Cancer Awareness Month.

The ICA urges everyone from 50 (or over 40, if there is a family or personal history of colon cancer, polyps or a disease of chronic bowel inflammation) to 75 to be screened annually with a simple free test to discover tiny amounts of blood in the feces, which can be a sign of a tumor. If the result is positive, the patient will be referred for an invasive endoscopic exam, either a sigmoidoscopy to look at the lower section of the bowel or a colonoscopy to view the entire bowel. If polyps are found, they can be removed by a tiny wire connected to the endoscope, thus eliminating the potential for it to become malignant.

ICA director-general Miri Ziv recommended several ways to reduce one’s risk of getting colorectal cancer: eat less animal fat; eat significant amounts of fibers from whole wheat and brown rice; eat many fresh vegetables (especially carrots) and fruits rich in antioxidants and fiber every day; don’t smoke; maintain normal weight; and exercise daily.

But the research results of Boland and Niv present a greater hope that one day a vaccine will be available that can prevent a good percentage of the cases of colorectal cancer from developing.

“[The results] are very exciting, and a offer a new hypothesis,” said Niv. “If true, there then exists the possibility of developing a vaccine against the JC virus which would provide immunity to it and in turn prevent a significant percentage of the instances of colorectal cancer.”


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