Ask the expert: Dr. Sing on colorectal cancer

Colorectal cancer (CRC) is one of the most common forms of cancer in the U.S. While CRC is often associated with older adults, it’s important to understand that CRC can impact anyone. In fact, in recent years, there has been an emerging trend of younger adults being diagnosed with CRC, highlighting the importance of awareness across all age groups.

Early detection is key in the fight against colon cancer. By identifying and addressing the disease in its early stages, treatment outcomes can be significantly improved. Your healthcare provider can help you determine when and what type of CRC screening is right for you.

To help you learn more about CRC, we spoke with Dr. Nicola Sing, MD, clinical lead at Labcorp and board-certified family medicine physician with extensive experience in primary care, urgent care, hospice and military medicine. Below, Dr. Sing discusses early symptoms of CRC, different types of CRC screening to consider with your healthcare provider and more.
 

How does CRC usually start?

Most colorectal cancers begin as a “bump” or growth in the lining of the intestine called a polyp. Some polyps are benign like moles on your skin and don’t pose a threat. But advanced adenomas (i.e., precancerous polyps) have features associated with more aggressive risk. The risk of polyps progressing to malignancy also increases as the number and size of polyps in the colon increases.
 

The goal of CRC screening is to proactively find and remove high-risk precancerous polyps before they progress and detect cancers in the early stages of disease when treatment is most likely to be most effective. The stage at which CRC is detected can have a dramatic impact on prognosis.
 

What are the most common first symptoms of CRC?

CRC often has no symptoms at all in the early stages when screening is most effective. As the cancer progresses, patients may experience symptoms such as:
 

• Rectal bleeding
• Dark black, tarry stools
• Change in bowel habits
• Abdominal discomfort or pelvic pressure
• Unintentional weight loss or fatigue associated with iron-deficiency anemia

Who should screen for CRC? What are the risk factors for CRC?

Some of the major organizations issuing guidelines for CRC screening include the United States Preventive Services Task Force (USPSTF), the American Cancer Society (ACS), the American College of Gastroenterology (ACG) and the American Gastroenterological Association (AGA).

These organizations generally agree that people at average risk should consider beginning CRC screening at age 45 and certainly plan to initiate screening by age 50. After the age of 75, the decision regarding whether and how to screen warrants further discussion between the patient and the provider about the benefits and potential risks of continuing to screen. Anyone with a first-degree relative (e.g., parent or sibling) who had CRC is at increased risk of developing it themselves. They should begin screening at age 40 or 10 years prior to the age at which that relative was diagnosed (whichever is earlier).

Other risk factors for CRC may include:

• Obesity or being overweight
• Type 2 diabetes
• Long-term diet high in red meats and processed meats
• Smoking
• Moderate to heavy alcohol use
• Age (CRC is more common after age 50)
• Race/ethnicity (e.g., American Indian, Alaska Native, African American, Ashkenazi Jews)

Is there a rise in colon cancer cases among younger women? What are the potential factors contributing to this trend?

Early-onset CRC (before age 50) is indeed occurring at a higher rate over the past 20-30 years, particularly in women. Researchers continue to pursue answers as to why this may be. For example, one possibility includes the wide variety of factors affecting the gut microbiome such as antibiotic use.

In 2018, the ACS officially lowered the age at which CRC screening should begin for adults at average risk from 50 to 45 years old with the goal of preventing delayed diagnosis in younger adults. All adults could benefit from considering their gut health and planning to begin screening at the appropriate age.

Can there be a genetic link to colon cancer?

There are some heritable syndromes associated with a significantly increased risk of developing CRC. Hereditary nonpolyposis colon cancer (HNPCC, or Lynch syndrome) and familial adenomatous polyposis (FAP) are two such syndromes. Discussing the details of your family history with your healthcare provider can help determine next steps that is in your best interest.

How do you screen for CRC? What options are available for CRC screening?

“I find it most useful to think of CRC screening options as either a 1-step or 2-step approach,” says Dr. Sing. “Depending on the individual patient, some options may be a more appropriate fit than others.”
 

One-Step CRC screening

Colonoscopy is the most effective screening option available. The entire colon is examined, and polyps can be both detected and removed during a single procedure. As clearly stated by the ACG, it is also “the final common pathway” for any abnormal findings on non-colonoscopy screening tests. If the results are all reassuring, follow-up screening colonoscopy is typically recommended at 10-year intervals.

“While this approach is considered the most effective, many patients may face barriers to completing a colonoscopy,” says Dr. Sing. “Fear of the procedure, time constraints, cost and access to care can all play a role in a patient’s ability to follow through on a recommendation for screening colonoscopy.”

Two-Step CRC screening

1. Stool-based tests are convenient because you can collect a stool sample at home and send it to a lab. There are different types of stool-based tests for colon cancer screening, including:

• Fecal immunochemical tests (FIT): A noninvasive screening test done annually that uses antibodies to detect traces of blood in the stool
• Multitarget stool-based DNA tests: A noninvasive screening test done every 1-3 years that looks for DNA markers associated with CRC and advanced/precancerous adenomas
  
  

2. Direct visualization screening options include CT colonography (uses special X-rays to create detailed images of your colon) or flexible sigmoidoscopy (procedure examines the lower part of your colon with a flexible tube) every five years. Both procedures require bowel preparation. CT scans involve a degree of radiation exposure, and flexible sigmoidoscopy only examines part of the colon. Alternatively, the flexible sigmoidoscopy can be done every 10 years, provided a FIT test is also done annually.

Dr. Sing notes that any positive or abnormal results on any non-colonoscopy screening tests require further evaluation with colonoscopy. She also emphasizes that “the best CRC screening method is the one you are most willing and able to complete.”

Why doesn’t everyone just screen with a stool-based test since they’re more convenient?

Stool-based tests are generally recommended only for people with an average risk for CRC.  If you have a higher risk due to family history, personal medical history, or other factors, your provider may recommend colonoscopy as your first-line screening option. Colonoscopy is a more effective screening method for high-risk individuals because it can detect both cancer and precancerous polyps, and any polyps found can be removed during the procedure.

Clinical guidelines recommend colonoscopy as the primary CRC screening method for patients at increased risk for CRC such as those with:

• Personal history of CRC or prior positive screening tests
• Family history of CRC or advanced adenomas
• Hereditary CRC syndromes (e.g., FAP or HNPCC/Lynch syndrome)
• Inflammatory bowel disease (IBD), such as ulcerative colitis or Crohn’s disease
• Cystic fibrosis
  
  

Why doesn’t everyone just screen with a colonoscopy since it’s the gold standard?

A colonoscopy is an invasive procedure that requires more time, effort and preparation to complete overall than the stool-based screening options. Here’s what the process typically involves:

• Bowel preparation: You’ll need to follow a special diet and drink a cleansing solution to prepare your bowel for the procedure. This can take some time and effort
  
• Sedation: Most people are provided with some degree of sedation during a colonoscopy. This helps them relax and feel more comfortable during the procedure, making it easier for the provider to perform the exam. Sedation is generally safe, but it’s important to discuss any concerns you have with your provider
  
• Risk: As with any invasive procedure, there are potential risks associated with a colonoscopy. Bleeding can occur, especially if polyps are removed during the procedure.  In rare cases, the procedure can cause a small tear or hole in the wall of the colon called a perforation. While uncommon, complications from sedations can occur. It is important to have someone drive you home after the procedure as sedation can affect your ability to drive safely
  
  

It’s also important to be aware that scheduling a colonoscopy may require some planning. Access to providers can vary, and you’ll likely need to take time off work for the procedure.

Can I talk to my gynecologist about CRC screening, or should it be my primary care provider (PCP)?

People typically think of pursuing discussions related to cancer screening with their PCP, who is trained to evaluate and treat a wide range of health conditions. PCPs can include providers trained in family medicine, internal medicine, gynecology, pediatrics and geriatrics. Any PCP is well-suited to counsel and refer patients for CRC screening. It’s also likely that patients at increased risk of developing CRC could be referred for CRC screening by other specialists involved in their care, such as their gastroenterologist or oncologist. Getting the screening done is far more important than which provider orders it.
 

How can I reduce my risk of getting colon cancer?

Dr. Sing shares three approaches to helping patients reduce their risk of CRC:

• Get screened according to the guideline recommendations. “Don’t wait for symptoms of advanced disease,” says Dr. Sing
• Avoid or address modifiable risk factors associated with increased risk of CRC. These risk factors can include red and/or processed meat intake, obesity, tobacco use and alcohol use
• Increase protective factors. Regular physical activity, as well as a diet high in fruits, vegetables, fiber and dairy products, can help protect against the risk of CRC

Additionally, while some medications, such as aspirin, are associated with lower CRC risk, they are not routinely recommended for everyone. Always consult with your provider for personalized advice and discussions about the risks and benefits of any medication.

Choosing the right CRC screening method for you

If you’re 45 years of age or older, the time to screen is now, says Dr. Sing. “Even ‘healthy’ people with no risk factors can and do get cancer,” she adds.

Remember: The best screening method is the one you are most willing to complete. “Though the thought of CRC screening may seem unpleasant, the risks of not screening are far more so,” says Dr. Sing.

While colonoscopy screening is the gold standard, screening tests like Labcorp’s ColoFIT Home Collection Test can provide a comfortable, convenient alternative if needed. The test detects hidden blood in the stool and does not require any special preparation. Not sure where to start? Here’s a step-by-step guide for at-home colon cancer testing.

Regardless of how you choose to approach CRC screening, your healthcare provider can help you navigate your options and answer your questions. To help inform conversations with your healthcare team, explore more of our CRC screening resources and educational content.