In the longer term, he said, nurses and technicians will be able to use self-propelling colonoscopes; an endoscopist will only get involved if the imaging reveals polyps that need attention. And computed tomographic colonography, also known as virtual colonoscopy, will make imaging studies much more acceptable to a wider pool of patients.
Computed tomographic colonography employs standard CT scanning to created 3-D images similar to those seen through a colonoscope. The colon is inflated with air during the study, which takes only 10–20 minutes and requires no sedation.
“Both the DNA test and virtual colonoscopy will become options for screening, and perhaps very soon,” Dr. Winawer said. “They are both being used on an ad hoc basis at a number of institutions and may get into the screening guidelines at some point.”
There are also demographic disparities to address, Dr. Levin said. “African Americans have a higher incidence and a higher mortality from colorectal cancer. It may be a mix of biology—the cancers themselves may be different—and access to medical care. There is evidence that screening rates are not as good in underserved populations, and that adjuvant therapy might not be given as aggressively to minority populations.”
Again, he said, education of patients and physicians is key. While it's unreasonable to expect every primary care physician to spend 5 minutes discussing the importance of screening with every eligible patient, “It's not unreasonable to take 7 seconds and give a simple message: 'Don't die of embarrassment. Get screened.'”
ELSEVIER GLOBAL MEDICAL NEWS
Trends in Other Cancers Get Noticed
The decline in colorectal cancer grabbed the most attention in the American Cancer Society's 2007 report, but the paper also highlighted some interesting trends in other gastrointestinal cancers.
Gastric cancer decreased slightly, continuing its dramatic 60-year decline, said Dr. Alfred Neugut. “Gastric cancer was the No. 1 cancer in the U.S. for years. Now it's almost negligible. The reasons probably are dietary, reflecting refrigeration and the increase in the consumption of fresh foods, rather than smoked and cured foods that contained cancer-causing nitrates and nitrites.”
There is also some speculation that the widespread use of antibiotics in childhood has decreased the prevalence of Helicobacter pylori, leading to decreased rates of gastric cancer in adults.
This cancer is still on the rise worldwide, however, said Dr. Sidney Winawer. “This is especially true in China, and probably is related to the prevalence of H. pylori.” American physicians may see more stomach cancer as immigration increases, he added.
There have been no significant improvements in pancreatic cancer incidence or mortality, the report noted. It is not as common as other cancers (it ranks last in incidence for males and doesn't rank in the top 10 for women), but is a virulent killer, ranking fourth in mortality for both genders. The report predicts 33,000 deaths, equally divided between the genders, for 2007.
“These numbers [show] that we don't know much about pancreatic cancer,” said Dr. Neugut. The small declines that have occurred are probably related to a general decrease in smoking.
But there is reason for hope, Dr. Winawer noted. International studies are looking at the best methods of screening for the disease in familial pancreatic cancer. “The protocols include multiple tumor markers, CT scanning, and endoscopic ultrasound,” Dr. Winawer said. “Once we figure out how to detect it in these families, we may be able to apply those techniques to the general population.”
There have been a very few minor advances in treating the disease, but the expense is enormous and the payoff, minimal, said Dr. Bernard Levin. “We are measuring gains in weeks of survival.”
Overall esophageal cancer rates are steady, but this trend masks changes within the disease, said Dr. Neugut. “Adenocarcinoma continues to increase, but squamous cell carcinomas are decreasing, and they are really compensating for each other in terms of the overall incidence.” Increasing obesity and untreated gastroesophageal reflux disease leading to Barrett's are probably the driving forces behind the rise in esophageal adenocarcinoma. The decrease in squamous cell cancer is probably related to the decline in smoking, he said.
The ACS report estimates more than 19,000 new cases of liver cancer for 2007, the majority of which will occur in men. Liver cancer had been increasing up until about 1999, the report said, but now seems to be stabilizing. The incidence of the disease is directly related to the prevalence of hepatitis C infections, Dr. Neugut said.