By David Himmel
March is Colorectal Cancer Awareness Month, and here’s what you need to know: Colorectal cancer is tricky. Complicated, really.
For starters, it’s really two cancers. Colorectal cancer is the combined term used to reference colon cancer and rectal cancer, but there are many similarities in risk factors, symptoms, diagnosis and treatment.
The polyps that can cause colorectal cancer hide in a part of the body that is difficult to access. Put bluntly, it’s where the sun don’t shine and even where a colonoscopy can have a hard time scoping.
Typically, with many other cancers, early-stage detection means a better survival rate. But five-year survival rates were better for some stage-three colon cancers than for some stage-two cancers, according to a study conducted by the American Cancer Society (ACS). The leaders of this study have no idea why. What’s more is that the biological causes and risk factors in different ethnicities and genders do not come with reasonable explanations either.
What is known, however, is that colorectal cancer is common. It is the second leading cancer killer in the United States behind lung cancer, according to the National Cancer Institute (NCI). One in 20 men and women will develop colorectal cancer. The ACS predicts that 136,830 cases will be diagnosed this year; of those, 50,310 people will die as a result.
The good news is that the death rates are dropping. Between 2006 and 2010, there was a 2.5 percent decrease in colorectal cancer deaths in men and a 3 percent decrease in women. Colorectal cancer is a highly preventable cancer,” says Laura Bianchi, MD, a gastroenterologist at NorthShore University HealthSystem.
“One thing I like to do is empower patients,” Bianchi says. “We have a really powerful tool [colonoscopies] to prevent the second leading cause of cancer (among men and women combined). We can detect and remove precancerous lesions—colon polyps—so we’re not just detecting early cancer, we’re preventing that cancer.”
Both modifiable risk factors and nonmodifiable risk factors play a part, Bianchi says. Modifiable factors would be things like tobacco use, obesity, physical inactivity and diet, while nonmodifiable factors are things like age, race and sex.
Current research suggests that diet and lifestyle changes, including a diet high in fruits, vegetables and whole grains, regular exercise and controlling body fat, could prevent colorectal cancer by 45 percent. According to the ACS, cases of this cancer have increased by 1.8 percent in adults younger than 50. An uptick in sedentary lifestyle among younger Americans may be the culprit.
Family history is also a variable. Knowing one’s history is powerful information, although there is no hard evidence that shows genetics play a role in one’s risk—unlike diabetes and heart disease. It’s the nonmodifiable factors that make a greater understanding of this particular brand of cancer so elusive.
“African Americans have a higher risk of developing colorectal cancer and are, on average, younger at the time of diagnosis [than other ethnicities].” African Americans are also diagnosed with later-stage disease and have a lower survival rate,” Bianchi says. “Women have a similar risk of developing colorectal cancer as men, but are diagnosed at an older age. Women are also more susceptible to the effects of tobacco use. We don’t know why this is, but we’re trying to understand why colorectal cancer behaves differently in men and women.”
All this makes prevention and screenings even more important. While screening has helped bring the number of reported cases and deaths down over the last several years, Bianchi says that the number of people getting screened is not as high as it should be.
In the United States, approximately 50 percent of adults 50 years old and over have not been screened. “When we look at the numbers, more specifically, locally—the North Shore population—less than 2/3 will undergo screenings. This lags behind screening for other cancers,” she says. “We’re always trying to enhance compliance.”
For average risk men and women, the recommended age to begin routine screening is 50. Bianchi says African Americans should start at 45. Individuals with a family history of colon polyps or colorectal cancer or a personal history of inflammatory bowel disease, such as Crohn’s, should consult with a physician about when to start screening.
Bianchi blames fear of the unknown on why more people don’t get screened. Also, the process of preparing for a colonoscopy terrifies many. “A colonoscopy is an invasive procedure. But people are most worried about the bowel preparation,” she says.
So, she is trying to remove all of the obstacles that keep patients from going through with screening and also trying to optimize the results of the procedure. In order to clean out the entire colon adequately, the bowel preparation prior to a colonoscopy is split over two days. Half the flush is done the night before, and the other half is done the next day.
“The right colon is where the subtle polyps reside, and a colonoscopy is less protective against colorectal cancer in the right colon,” Bianchi says. “We find that if we fast overnight, the GI (gastrointestinal) tract secretes juices that become adherent in the right colon, making it difficult to see polyps. The split dose lets us flush [the bowels] in the morning and see clearer.”
Seeing the colon clearly is the key to further reducing the number of reported colorectal cancer cases and deaths. The more people who get screened means that more people will be able to prevent the cancer from becoming invasive. Screening also provides necessary data that professionals like Bianchi need in order to improve detection and treatment.
“We know that 10 percent of colon polyps, if not removed, will progress to colorectal cancer,” Bianchi says. “With screening and removal of precancerous polyps, colorectal cancer is 90 percent preventable.”
In the March 20 issue of the New England Journal of Medicine, results of a clinical trial led by the Mayo Clinic show unprecedented rates of precancer and cancer detection through a noninvasive test called Cologuard.
Cologuard, developed by Mayo Clinic and Exact Sciences, analyzes a patient’s stool for altered DNA shed during digestion. Altered DNA is known to occur within colorectal cancers and precancerous polyps. The test also examines the stool for traces of blood, which can also be an indication of cancer.
Researchers are hopeful that the ease of use and accessibility provided by the Cologuard test will lead to an increase in the number of people choosing to have screenings.
Published on March 19, 2014