Colorectal Cancer Screening

Happy March Everyone!

This month’s discussion revolves around colorectal cancer screening. Colorectal cancer (CRC) is the only cancer we can prevent. I repeat—CRC is the ONLY cancer we can prevent!! How is this possible? All other cancer screens provide early detection, but the neoplasm is already present. Colonoscopies find potentially pre-cancerous polyps or growths that have not converted to malignant lesions. The gastroenterologist can then remove these growths, thus preventing cancer from developing. Unfortunately, too many people do not want to undergo the prep, thus delaying or not receiving this potentially life-saving procedure.

CRC symptoms include a change in bowel habits, abdominal cramps that will not dissipate, blood in the stool, incomplete emptying of bowels after movements, or unexplained weight loss. Any of these symptoms warrants evaluation. Being diagnosed with Inflammatory Bowel Disease, i.e., Crohn’s disease or Ulcerative Colitis; Having hereditary factors such as a family history of a loved one with CRC or polyps, Lynch Syndrome or Familial adenomatous polyposis, or ever receiving radiation treatment to the abdomen may increase risk of colon cancers. Anal warts due to HPV infections can also increase the risk of anorectal cancer. Healthy diets and those with dairy and vitamin C supplementation may decrease risk, whereas smoking and increased daily alcohol consumption may worsen one’s chances of developing CRC. Multiple screening tools have been used in the past – just a few will be discussed below.

Historically, we used to screen for colon cancers using barium enemas. Heme occult cards to look for blood and perform flexible sigmoidoscopies in the office were then utilized. The scopes looked for cancer 60 cm from the anus, where 75% of cancers would start. Using the stool cards for blood detection would require a full GI workup if positive. Knowing we could miss up to 25% of lesions, colonoscopies became the gold standard. They are comprehensive but require more preparation and sedation to undergo safely. Also, biopsies are performed if any lesions are found.

The preparation consists of a liquid diet the day before and liquid or tablets to clean the colon. The following day the test is performed. One cannot eat and must require a friend or family member to take them to and from the testing center due to the sedation one receives. Symptoms after the procedure usually include a slight gas increase and sleepiness until the sedation wears off. Risks include effects or adverse reactions from the sedation, bleeding, or bowel perforation if biopsies are performed. Results are usually known within 5-10 days, depending on the number of biopsies taken. The results determine the future frequency of colonoscopies required to continue to screen for CRC safely.

Cologuard is a relatively new test to detect abnormal DNA from cancerous lesions. It screens for ten different genetic mutations and blood in the stool. It does miss pre-cancerous cells, whereas colonoscopies do not miss these pre-cancerous lesions. The benefits of Cologuard are that it is cheaper, non-invasive, and can be performed at home by properly collecting a stool sample and sending it to the lab. This test is indicated for only AVERAGE-risk patients. Any high-risk patients require obtaining a colonoscopy. The specificity is around 87%, and sensitivity is about 92%, whereas colonoscopies are higher than 95% for both parameters.

CRC is increasing in frequency, especially in younger patients. We lost Chadwick Boseman of Black Panther and 42 fame at the age of 44 due to CRC. The proportion of patients diagnosed with CRC younger than 55 increased from 11% in 2011 to 20% in 2019. Current guidelines advocate screening at age 45. Screening for patients younger than that may potentially be implemented, especially if they are genetically predisposed to developing CRC or have conditions like Ulcerative colitis at an early age where a 10-year screen from diagnosis is indicated. I urge everyone to assess their risk factors and discuss which screen is appropriate with their physician. Don’t forget, colonoscopy is the gold standard, and to me is worth the time, cost, and inconvenience to know that I am CRC-free!!!!

Author

Dr. Frank Mazza Dr. Mazza has been a Houston resident since 1979. He earned his undergraduate degree at the University of Texas at Austin, and he went on to earn his medical degree at the University of Texas Medical School in Houston. He completed his family practice residency at the Memorial Southwest Family Practice residency program. Dr. Mazza has often been recognized as a favorite local family physician in Texas Monthly magazine and other publications. Some of Dr. Mazza’s favorite hobbies include reading, sports, and music. He and his wife are proud parents of three daughters.