Screening is the best preventative for colorectal cancer

March was Colorectal Cancer Awareness Month and the perfect time to heighten our understanding of colorectal cancer.

Colorectal cancer (CRC) is the third-most commonly diagnosed cancer as well as the third-leading cause of cancer deaths in the United States and in Minnesota. It is preventable.

Signs and symptoms of CRC include change in bowel habits (diarrhea, constipation, or narrowing of the stools lasting several days); incomplete emptying; rectal bleeding or blood within the stool (bright red blood or maroon or dark stool); abdominal cramping or pain; weakness or fatigue (anemia); and weight loss.

CRC develops slowly over the course of years, and 95% begin as precancerous polyps inside the colon or rectum. Polyps can grow from the inside of the colon or rectal wall, through the layers of the colon, and eventually to nearby lymph nodes and other organs. 

CRC is staged based on the TNM classification: T (depth of tumor penetration through the colon wall), N (lymph node involvement), and M (metastasis or distant spread of cancer outside of the colon).

CRC diagnosis is made by biopsy, and its subsequent staging is determined after obtaining a CT scan of the chest, abdomen, and pelvis. Overall five-year survival is excellent for early CRC (90% for Stage 1, 80% for Stage 2, 70% for Stage 3, and 14% for Stage 4). Risk factors include: 

1) age (risk increases with age, as 90% of CRC is diagnosed among people 50 years or older); 

2) male gender (CRC incidence is greater for men than women); 

3) personal history of colon polyps or cancer; 

4) family history of colon cancer and genetic syndromes (Familial Adenomatous Polyposis or Lynch Syndrome); and 

5) inflammatory bowel disease (IBD), such as ulcerative colitis or Crohn’s disease. Obesity, physical inactivity, smoking, heavy alcohol use, and diet high in red and processed meats have also been linked to CRC risk.

There is strong evidence that the most effective prevention of CRC in average risk individuals is screening. Historically, guidelines have recommended screening begin at age 50 in the average risk population, likely contributing to decreasing rates of colorectal cancer since 2006.

In contrast and for unknown reasons, CRC incidence and mortality have been increasing in individuals aged 20-49, especially in the African American population. In addition, African Americans are more likely to die from CRC when compared to other races/ethnicities. 

In Minnesota, incidence and mortality are highest for American Indians (63%), followed by African Americans (40%), then Hispanics and Caucasians (39% each).

Screening guidelines for the average risk population have been published by several organizations, as outlined below:

¹USPSTF (US Preventive Services Task Force); ²ASCRS (American Society Colon Rectal Surgeons); ³ACS (American College Surgeons); ⁴USMSTF (US Multi-Society Task Force)

*criteria for screening in this age group individualized based on patient preference, life expectancy, overall health and prior screening history

For those at increased or high risk, referring to the factors discussed above, screening guidelines generally recommend:

1) If family history of CRC, begin screening at age 45 or 10 years earlier than family member diagnosed with CRC.

2) If family history of familial or genetic syndrome, begin screening in teenage years or early 20s, with surveillance colonoscopy recommended every two years after initial examination.

3) If polyps found on initial colonoscopy, surveillance examination should be scheduled in one, three or five years depending on size, type and number of polyps.

4) If personal history of IBD, initial colonoscopy is recommended eight years after IBD diagnosis with surveillance examination every one to two years, depending on risk factors and findings on prior colonoscopy.

Screening tests are divided into two types: 

*Any abnormal test should be followed with colonoscopy

If you have any questions regarding your risk of CRC, please talk with a healthcare provider to discuss your best screening option. Please remember and always keep in mind that the best screening test is the one that gets done.

Sharon Luster Dykes, MD, FACS, FASCRS is a dual board-certified colon and rectal surgeon. She owns her independent surgical practice, Minnesota Colon, and Rectal Surgical Specialists. She earned her Bachelor’s and Medical Degrees from Brown University and completed General Surgery Residency and Colon and Rectal Surgery Fellowship at the University of Minnesota. She currently serves as a Senior Oral Examiner and a Written Examination Committee member for the American Board of Colon and Rectal Surgery.