New technology puts the beginnings of colon cancer into focus
The Hartford Courant
Using new imaging technology, doctors at the University of Connecticut can now see with unprecedented clarity the odd-looking groups of raised cells that may be the beginnings of colon cancer.
Close-focus/narrow-band imaging scopes may one day help provide clues to the genesis of cancer ” and help test new treatments designed to stop cancer in its tracks, the researchers say.
The new scopes allow doctors to get a better look at aberrant crypt foci, or ACF ” raised clusters of cells with a distinctive slit-like opening that can form on the colon wall. ACF cells are found in people with colon cancer and are more likely to be found in people with a family history of colon cancer. Occasionally, they turn into adenomas, or polyps that become cancer.
But most ACF cells do not lead to a malignancy, and their presence alone does not predict whether someone will develop colon cancer.
“Most of these early changes probably don’t go anywhere,” says Dr. Joel Levine, co-director of the colon cancer prevention program at the University of Connecticut’s Health Center. “But we are looking for ways to differentiate between good apples and bad apples.”
Levine is quick to point out that the new scopes can’t spot the bad apples yet. But he says the technology has already provided some hints about why good cells go bad.
In the past, lenses used in colonoscopes could detect ACF cells only if they were positioned in just the right way relative to the colon wall.
“But if you brought the lenses away from the top of the surface, you lost the image,” Levine says. “They were not a practical way to find tiny early changes.”
The new generation of close-focus scopes made studying ACF cells much easier. The researchers could detect objects at a close distance and keep them in focus as the scope was moved away from the surface of the colon.
Researchers are interested in ACF cells for several reasons. It turns out that counting the cells is a good way to study the effectiveness of cancer prevention programs.
In the past, scientists have tried to track tumor growth in mice when attempting to assess whether certain diets or drugs might prevent or treat cancer. But tumors are difficult to track and must be confirmed with costly biopsies.
With a close-focus scope, researchers can get an accurate count of ACF cells. A decrease in the ACF cells on the colon wall, in theory, means the subject will be at a decreased risk of colon cancer.
For instance, the university’s Cancer Prevention Program will participate in a trial to determine whether a combination of ibuprofen, sugars and cholesterol-lowering drugs called statins will reduce the number of ACF cells ” and possibly lower the risk of colon cancer.
The narrow-band imaging component of new scopes gives researchers another potent research tool, Levine says. “Narrow band” refers to the shorter wavelength of light emitted by the scope, which can be absorbed by red blood cells.
A narrow-band scope can reveal the presence of tiny blood vessels within an ACF cluster. Those blood vessels could indicate angiogenesis ” or the creation of new blood vessels that cancer tumors need to grow. The generation of additional blood vessels in the ACF cells could provide a biological marker that will enable scientists to determine which cell clusters are harmless and which ones are precursors to potentially deadly colon cancer.
If the theory is born out by research, doctors may have a way to detect the earliest trace of cancer ” and possibly not just in the colon. Japanese researchers already have identified early cellular changes that lead to throat cancer, and similar abnormalities may occur in other cancers, Levine says.
While technology may help in research, some doctors say it is not clear how it can be applied in everyday medicine.
“The $64,000 question is whether we can figure out some way to bring these new insights to bear onto the condition of the average patient,” says Dr. Jonathan Sporn, attending physician at St. Francis/Mount Sinai Regional Cancer Center in Hartford, Conn.
For instance, asks Dr. Robert Flescher, a gastroenterologist at Hartford Hospital, will the ability to identify the earliest trace of colon cancer end up saving more lives than a typical colonoscope, which can identify and remove cancerous polyps?
“The question is, what do you do” when you find the aberrant cells, Flescher said.
Sporn says that at some point we have to ask whether the investment in procedures that catch cancer at a much earlier stage is actually going to prevent cancer and save a significant number of lives.
Levine argues that by identifying people at high risk of developing cancer, doctors will be able to aggressively advocate colon cancer prevention strategies such as changing one’s diet to include more calcium and Vitamin D and less red meat, and exercising regularly.
“You would sort out people at higher risk and lower risk, and then maybe don’t have to examine those at low risk as much,” Levine says. “You will have a natural (method) of sorting out people for prevention, rather than for treatment.”
– Colorectal (colon and rectal) cancer almost always develops from precancerous polyps ” abnormal growths ” in the colon or rectum. Screening can find the growths so they can be removed before turning into cancer.
– Aside from skin cancer, colorectal cancer is the third most common cancer in both men and women ” after prostate and lung cancer in men, and after breast and lung cancer in women. It primarily affects people age 50 and older.
– The American Cancer Society estimates 104,950 new cases of colon cancer in the United States in 2005, and 40,340 new cases of rectal cancer, and a combined total of about 56,290 deaths.
– The federal Centers for Disease Control and Prevention estimates that if everyone age 50 and older were screened regularly, as many as 60 percent of deaths from colorectal cancer could be prevented.
– The use of colonoscopies as a routine diagnostic test saves many lives, but colonoscopies and other screening tests are not foolproof. Studies have shown that colonoscopies miss as many as one in five polyps smaller than 1 centimeter.
SOURCES: American Cancer Society, U.S. Centers for Disease Control and Prevention, Hartford Courant staff reporting
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