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Screening for Colorectal Cancer: Colonoscopy vs. At-Home Kits

Colon Cancer Waiting

Colorectal cancer is the third-leading cause of cancer deaths in the United States. It’s also the third-most common cancer diagnosed in American men and women, excluding skin cancers. About one in 22 men and one in 24 women will develop colorectal cancer at some point in their lifetime.

Yet, for all of its prevalence and devastation, colorectal cancer is also one of the most easily preventable types of cancer. Because it develops at such a slow rate—it can take up to 10 years for cancer to form in a polyp—it is possible to prevent 90 percent of colorectal cancer cases.

Timely and consistent screenings are recommended to begin at age 50 for both men and women at average risk for developing colorectal cancer (45 for African Americans, who are considered a slightly higher-risk population). The frequency of the screenings from that point depends on the test used and the results of that test.

Screenings fall into two categories: stool tests and tests that visualize the colon directly, such as colonoscopy.

Stool tests, which can be done at home, may be preferred because they’re simple, safe, cost-effective and non-invasive. However, Maureen Hewitt, MD, assistant medical director of Penn Hematology and Oncology at the Abramson Cancer Center at Chester County Hospital, warns that there is a greater risk of a false negative test (not finding a cancer that is present) or a false positive test (testing positive for a benign reason) compared to the screenings that allow care providers to directly visualize the colon.

In addition, stool based screening tests need to be repeated every one to two years. By contrast, experts recommend a colonoscopy every 10 years for people at average risk as long as their test results are negative.

“With a colonoscopy, a physician is able to visualize the lumen of the bowel, and any abnormalities, such as polyps.  Polyps are removed before they have a chance to transform into a cancerous lesion,” Hewitt explained. “It becomes a direct means to prevent colon cancer.”

The disadvantage of a colonoscopy, Hewitt added, is the aggressive bowel preparation that’s required so that the physician is able to see the entire surface of the bowel. “If the bowel preparation is not adequate, it can obscure polyps and small tumors.”

The preparation was found to be one of the leading reasons why one-third of adults in the United States are not getting screened — many of them at high risk for developing colorectal cancer.

At-home kits may be preferred by patients for this reason, as they do not require as many dietary restrictions or as much preparation beforehand but according to Hewitt, a colonoscopy could be required regardless. “A positive stool test obligates moving forward with a colonoscopy,” she said.

The Colon Cancer Alliance reports that individuals at high risk for colorectal cancer are those with a family history of colorectal cancer, inflammatory bowel disease (such as ulcerative colitis or Crohn’s Disease), obesity, diabetes and, to an as-yet-unknown extent, cigarette smoking and alcohol abuse. Race also plays a role.

In 2011, in an effort to address the large population of Americans not getting colorectal cancer screenings, Carmen Guerra, MD, MSCE, FACP, an associate professor of Medicine at the Hospital of the University of Pennsylvania, and Michael Kochman, MD, FACP, a professor of Medicine, launched the Penn Medicine Abramson Cancer Center West Philadelphia Gastrointestinal Health Outreach and Access Program. The goal was to make colonoscopies more accessible and less intimidating to a largely African American, immigrant, and impoverished population.

“What we’re finding is the program has a 35 to 37 percent detection rate of adenoma polyps,” Guerra said. “That rate is a lot higher than we expected. The average is 20 to 25 percent. We think it’s because we’re targeting a higher risk population. These patients couldn’t access the screening before, so they tend to be a little older, about 60-years-old. And we know that there’s a close correlation between age and the development of colon cancer.”

The program uses electronic medical records to see who’s not showing up for their colonoscopy. A trained health care professional known as a patient navigator then contacts them and offers to help with whatever their reasons may be for not going. If they don’t speak English, a free translator is provided. If they’re particularly isolated or have trouble affording transportation to their appointments, they’re furnished with SEPTA tokens and an escort who stays with them from their front door to the screening and back home again. The navigator even follows-up once the biopsy results are available to ensure they’re communicated clearly.

Communication was an issue early on, Guerra shared. “We were finding that the instructions for how to prepare for the colonoscopy were not being followed correctly,” she explained. The problem was traced to the literature; it wasn’t clear enough. So, with a grant from the American Cancer Society, they created an instructional video and posted it on YouTube. “That’s proven to be a much better way to learn,” Guerra said, adding that the best way to find out which screening option is best and when to start screenings, is for patients to talk to their primary care provider.



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