Colorectal cancer remains a major cause of cancer morbidity and mortality, with over 140,000 new diagnoses and 50,000 deaths in the United States every year. Screening for colorectal cancer, however, has helped reduce colon cancer deaths and has been one of the major success stories of preventive healthcare in recent decades. Since peaking in the mid-1980’s at over 250,000 new cases per year, we’ve seen declining incidence and deaths due to colon cancer, with much of the improvement attributed to increased screening asymptomatic individuals.
ACS Calls for Screening to Begin at Age 45
The American Cancer Society (ACS) has recently called for changes in colorectal cancer screening by lowering the recommended age at which “average risk” patients (i.e. patients without significant family or personal history of colorectal cancer or precancerous polyps) should start being screened, from 50 years of age down to 45. Why the change?
In short, because we’re seeing more young people diagnosed with colorectal cancer than we have in the past. While the incidence of colorectal cancer in older individuals (the target of our screening efforts to date) has declined significantly, it has increased dramatically in those younger than 55 years old, with a 50% increase in incidence over the last two decades.
The reason for this increase among younger individuals has not yet been readily identified, but nevertheless seems an appropriate focus for improvement.
Many Groups Offer Screening Guidelines
In addition to the ACS, there are several other well-respected organizations that publish relevant guidelines including the U.S. Preventive Services Task Force; Multi-Society Task Force of Colorectal Cancer, which includes the major gastroenterology professional societies; American Academy of Family Physicians; and the American College of Physicians. To date, all of these other groups suggest starting screening at age 50 for average risk individuals (with the notable exception of the recommendation of the Multi-Society Task Force of Colorectal Cancer to start screening in African-Americans at age 45).
The recommendation from the ACS is the first one to depart from current screening guidelines. The call for change stems from the use of the most up to date incidence data that was then used to model various screening strategies. Although most of the guidelines from the other groups have been updated within the last several years, they did not have this most recent data available. It remains to be seen if the other guideline organizations will follow suit and also lower their recommended starting age, but many experts think it is likely.
Guidelines Otherwise Remain Consistent
Similar to guidelines from other organizations, the ACS suggests doing one of the following:
- Colonoscopy every 10 years
- Flexible sigmoidoscopy every five years
- CT colonography (a CT scan that is intended to evaluate for cancer or precancerous growths) every five years
- A stool test looking for the presence of blood, done every year
- A stool test looking for blood and/or certain DNA changes that are associated with colorectal cancer, done every three years
Comparing Screening Methods
All of these screening methods have pros and cons. Colonoscopy is the only option that allows for both diagnosis and removal of precancerous polyps, thus decreasing the likelihood of the development of colorectal cancer down the road. The ACS guidelines emphasize that if any of the non-colonoscopy-based tests are abnormal, that colonoscopy should then be done in short order for further diagnosis and management.
Understanding Risk Factors
Perhaps the strongest known risk factor for developing colorectal cancer is family history. If you have first-degree family members (siblings, parents, children), or multiple second-degree family members (aunts, uncles, grandparents), who have had colorectal cancer, particularly under age 60, your risk is significantly higher. Screening is advised at younger ages for such patients, generally starting at age 40, or 10 years earlier than the age of diagnosis of the affected family member.
Family history, however, is by no means the whole story. Most people who are diagnosed with colon cancer do NOT have a family history. There are other modifiable risk factors that have been identified for colorectal cancer, including:
- Alcohol use
- Physical inactivity
- High fat diet
- Low fiber diet
- Diet high in red meat and smoked/processed meats
If we are going to be serious about trying to further decrease the incidence and toll of colorectal cancer, we should all start colorectal cancer screening at an appropriate age, and lead an active, healthy lifestyle that includes a mostly plant-based diet.