Colorectal Cancer Screening: Colonoscopy vs Cologuard vs FIT | Philadelphia

TL;DR30-second take

Colorectal cancer screening now starts at age 45 for average-risk adults, and earlier with a family history. Colonoscopy every 10 years is the most complete option because it both finds and removes precancerous polyps, preventing cancer rather than only detecting it. Stool tests (FIT yearly, Cologuard every 3 years) and newer blood tests are non-invasive alternatives, but a positive result still needs a colonoscopy. The best test is the one you will complete. Fishtown Medicine helps you choose and refers colonoscopy to in-network GI.

TL;DR: Colorectal cancer is one of the most preventable cancers, and screening now starts at age 45 for average-risk adults, earlier if it runs in your family. The reason it is so preventable is that it usually grows slowly from polyps that can be found and removed before they ever turn into cancer. Colonoscopy is the most complete test because it both finds and removes those polyps in one procedure; stool tests like FIT and Cologuard and the newer blood tests are easier and non-invasive, but any positive result still has to be followed by a colonoscopy. The single most important thing is to get screened by some method, because the best test is the one you will complete. At Fishtown Medicine we help you pick the right option and coordinate it.

If you are turning 45, are overdue, or have been putting off colorectal screening because colonoscopy sounds unpleasant, this page is for you. There is more than one way to screen now, they are not equal, and understanding the trade-offs makes the decision easier. Here is how the options compare and how to choose.

When should colorectal cancer screening start?

For average-risk adults, colorectal cancer screening should start at age 45, a change from the old age of 50 that was made because colorectal cancer has been rising in younger adults.¹ Screening then continues at intervals that depend on the test and your results, generally through age 75, with individualized decisions after that.

Some people should start earlier or screen more often. A family history of colorectal cancer or advanced polyps, particularly in a first-degree relative, a personal history of inflammatory bowel disease, or certain genetic syndromes all move the starting age earlier and can change the recommended test and interval. This is why the right screening plan is individual, and why a conversation about your family history matters as much as your age.

What are the colorectal screening options?

There are several screening methods, and they fall into two groups: tests that look directly at the colon, and tests that check stool or blood for signs of cancer.

Colonoscopy examines the entire colon with a camera, and if polyps are found, they are removed during the same procedure. It is done every 10 years for average-risk people with a normal result, and it requires bowel prep and sedation. It is the only test that both screens and treats in one step.
FIT (fecal immunochemical test) is an at-home stool test done once a year that checks for hidden blood. It is simple, inexpensive, and non-invasive, and a positive result leads to a colonoscopy.
Cologuard (multitarget stool DNA test) is an at-home test done every 3 years that checks stool for both blood and DNA markers of cancer. It is more sensitive for cancer than FIT but has more false positives,² and a positive result leads to a colonoscopy.
Blood-based tests are the newest option, checking blood for tumor DNA. They are the most convenient, but they are less sensitive for the precancerous polyps that screening most wants to catch,⁴ and a positive result leads to a colonoscopy.
CT colonography (a virtual colonoscopy by CT scan) is done every 5 years and is an option for people who cannot have a standard colonoscopy.

Colonoscopy vs Cologuard vs FIT vs blood tests: how they compare

The tests trade completeness against convenience. This is the short comparison:

	Colonoscopy	FIT	Cologuard	Blood test
How often	Every 10 years	Yearly	Every 3 years	Interval still being defined
Where	Procedure with prep and sedation	At home	At home	Blood draw
Finds polyps?	Yes, and removes them	Detects some indirectly	Better than FIT, still limited	Weakest for polyps
Prevents cancer?	Yes, by removing polyps	Mainly detects	Mainly detects	Mainly detects
If positive	Definitive	Needs colonoscopy	Needs colonoscopy	Needs colonoscopy
Best for	Highest-yield screening; higher risk	Simple yearly average-risk screening	Non-invasive, more sensitive than FIT	Those who will not do other options

The key distinction is prevention versus detection. Colonoscopy prevents cancer by removing polyps before they become cancerous, which is a stronger goal than detecting cancer that has already formed.³ The stool and blood tests are screening tools that, when positive, always route back to a colonoscopy, so they are best understood as ways to decide who needs a colonoscopy rather than replacements for it.

Which colorectal screening test should you get?

The right choice depends on your risk and, frankly, on what you will complete:

Higher risk (family history, prior polyps, symptoms): colonoscopy is the clear choice, and often at an earlier age and shorter interval.
Average risk, and willing to do a colonoscopy: it is the most complete option, catching and removing polyps in one step every 10 years.
Average risk, but you will not do a colonoscopy: a stool test (FIT yearly or Cologuard every 3 years) is far better than no screening, with the understanding that a positive result means a colonoscopy follows.
You have avoided screening altogether: a blood test is the newest and most convenient option, and while it is weaker at catching precancerous polyps, getting screened at all is a large improvement over nothing.

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The theme is that the best test is the one you will complete. A perfect test you skip protects no one, while a good test you complete can prevent or catch a cancer early, when it is highly treatable.

How Fishtown Medicine approaches colorectal screening in Philadelphia

We start with your risk, your age, and your history, then match the test to both your medical picture and what you will realistically follow through on. For most people at average risk we walk through the honest trade-offs between a colonoscopy and a stool or blood test, and we make sure whatever you choose gets scheduled and completed, because the most common failure in colorectal screening is simply never doing it.

We do not perform colonoscopy ourselves; when one is the right test, or when a stool or blood test comes back positive, we refer to highly qualified gastroenterology specialists who are in network for you and coordinate the results into your plan. For complex or high-risk situations we compare notes across a network of specialists so the plan and the timing are right. Whether you are in Fishtown or Rittenhouse, or across the bridge in Cherry Hill or Moorestown, the aim is to make sure this highly preventable cancer is being screened for.

Guidance from the Clinic

"Colorectal cancer is one of the few cancers we can prevent outright, because we can find and remove the polyp before it ever becomes cancer. That is why I care less about which test someone picks and more that they pick one and finish it. If you will do a colonoscopy, it is the most complete option and you are set for a decade. If the idea keeps you from screening at all, a stool test or a blood test is far better than the nothing that too many people default to. My job is to help you choose and then make sure it happens."

Key Takeaways

Screening starts at age 45 for average-risk adults, lowered from 50 because colorectal cancer is rising in younger people; earlier with family history.
Colorectal cancer is highly preventable because it grows slowly from polyps that can be removed before they become cancer.
Colonoscopy is the most complete test, finding and removing polyps in one step every 10 years, and the clear choice for higher risk.
FIT, Cologuard, and blood tests are non-invasive alternatives, but any positive result still requires a colonoscopy.
The best test is the one you will complete - screening by some method matters far more than which one.
Fishtown Medicine helps you choose and refers colonoscopy to in-network gastroenterology in Philadelphia and South Jersey.

Advanced Cancer Screening - the broader early-detection picture, including Galleri and imaging
The Four Horsemen: The Diseases That End Most Lives - where cancer fits the longevity picture
Alcohol and Longevity - a modifiable colorectal cancer risk factor
Ultra-Processed Food - diet and colorectal risk
Preventive Care in Philadelphia - how screening fits a full prevention plan

Scientific References

US Preventive Services Task Force. "Screening for Colorectal Cancer: US Preventive Services Task Force Recommendation Statement." JAMA. 2021;325(19):1965-1977.
Imperiale TF, Ransohoff DF, Itzkowitz SH, et al. "Multitarget Stool DNA Testing for Colorectal-Cancer Screening." New England Journal of Medicine. 2014;370(14):1287-1297.
Zauber AG, Winawer SJ, O'Brien MJ, et al. "Colonoscopic Polypectomy and Long-Term Prevention of Colorectal-Cancer Deaths." New England Journal of Medicine. 2012;366(8):687-696.
Chung DC, Gray DM, Singh H, et al. "A Cell-free DNA Blood-Based Test for Colorectal Cancer Screening." New England Journal of Medicine. 2024;390(11):973-983.

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Frequently Asked Questions

Common Questions

Average-risk adults should start colorectal cancer screening at age 45, lowered from 50 because colorectal cancer has been rising in younger people. Screening generally continues through age 75, with individualized decisions after that. If you have a family history of colorectal cancer or advanced polyps, inflammatory bowel disease, or a genetic syndrome, you may need to start earlier and screen more often, so it is worth reviewing your family history with your physician.

Cologuard is a reasonable non-invasive option but it is not equivalent to a colonoscopy. It is more sensitive for cancer than the older FIT stool test, but it is weaker at detecting precancerous polyps, has more false positives, and, crucially, cannot remove anything; a positive result still requires a colonoscopy. Colonoscopy both finds and removes polyps in one step, which is why it is the more complete test. Cologuard is best for people who will not do a colonoscopy, where it is far better than no screening.

The newer blood-based tests detect tumor DNA in the blood and are the most convenient option, requiring only a blood draw. They can detect existing colorectal cancer reasonably well, but they are weaker at catching the precancerous polyps that screening most wants to remove, and a positive result still leads to a colonoscopy. They are most valuable for people who have refused every other form of screening, since screening by some method is far better than none.

There is no single best test for everyone; the best test is the one you will complete. Colonoscopy is the most complete because it both finds and removes polyps, preventing cancer, and it is the clear choice for higher-risk people. For average-risk people who will not do a colonoscopy, a yearly FIT or a Cologuard every 3 years is a strong alternative, and a blood test is better than nothing. Getting screened by some method is what matters most.

Deep-Dive Questions

Colonoscopy prevents cancer because most colorectal cancers develop slowly from benign polyps over years, and a colonoscopy can find and remove those polyps in the same procedure, stopping the cancer before it ever forms. Long-term follow-up of people who had precancerous polyps removed during colonoscopy showed a substantial reduction in colorectal cancer deaths, which is prevention in the truest sense.<sup>3</sup> Stool and blood tests, by contrast, look for signs that a cancer or a bleeding polyp is already present; they can catch disease earlier than symptoms would, but they cannot remove anything, so a positive result routes to a colonoscopy for the removal itself. This is the fundamental difference: colonoscopy is both the screening and the treatment, while the other tests are ways of deciding who needs that procedure. It is also why colonoscopy sits at the top for people at higher risk, where the chance of finding a polyp worth removing is greater.

The screening age dropped to 45 because colorectal cancer has been rising in adults younger than 50, a trend that has been building for decades and is not fully explained. Modeling by the US Preventive Services Task Force found that starting screening at 45 rather than 50 would prevent additional cancers and deaths with an acceptable balance of benefits and harms, which led to the updated recommendation.<sup>1</sup> The practical implication is that a large group of adults in their late 40s who were previously told to wait are now due for screening and may not know it. If you are between 45 and 50 and have not been screened, you are now within the recommended window, and it is worth acting on.

Family history changes the plan by moving the starting age earlier and often shortening the interval between screenings, because inherited risk raises the odds of developing colorectal cancer and of developing it younger. A first-degree relative (parent, sibling, or child) with colorectal cancer or advanced polyps typically means starting screening at 40, or 10 years before the age at which that relative was diagnosed, whichever comes first, and usually with colonoscopy rather than a stool test. Certain genetic syndromes, such as Lynch syndrome or familial polyposis, call for much earlier and more frequent screening and sometimes genetic counseling. This is why reviewing your family history is a core part of a screening decision, since it can substantially change both when you start and which test is appropriate.

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TL;DR30-second take

TL;DR: Colorectal cancer is one of the most preventable cancers, and screening now starts at age 45 for average-risk adults, earlier if it runs in your family. The reason it is so preventable is that it usually grows slowly from polyps that can be found and removed before they ever turn into cancer. Colonoscopy is the most complete test because it both finds and removes those polyps in one procedure; stool tests like FIT and Cologuard and the newer blood tests are easier and non-invasive, but any positive result still has to be followed by a colonoscopy. The single most important thing is to get screened by some method, because the best test is the one you will complete. At Fishtown Medicine we help you pick the right option and coordinate it.

When should colorectal cancer screening start?

What are the colorectal screening options?

There are several screening methods, and they fall into two groups: tests that look directly at the colon, and tests that check stool or blood for signs of cancer.

Colonoscopy examines the entire colon with a camera, and if polyps are found, they are removed during the same procedure. It is done every 10 years for average-risk people with a normal result, and it requires bowel prep and sedation. It is the only test that both screens and treats in one step.
FIT (fecal immunochemical test) is an at-home stool test done once a year that checks for hidden blood. It is simple, inexpensive, and non-invasive, and a positive result leads to a colonoscopy.
Cologuard (multitarget stool DNA test) is an at-home test done every 3 years that checks stool for both blood and DNA markers of cancer. It is more sensitive for cancer than FIT but has more false positives,² and a positive result leads to a colonoscopy.
Blood-based tests are the newest option, checking blood for tumor DNA. They are the most convenient, but they are less sensitive for the precancerous polyps that screening most wants to catch,⁴ and a positive result leads to a colonoscopy.
CT colonography (a virtual colonoscopy by CT scan) is done every 5 years and is an option for people who cannot have a standard colonoscopy.

Colonoscopy vs Cologuard vs FIT vs blood tests: how they compare

The tests trade completeness against convenience. This is the short comparison:

	Colonoscopy	FIT	Cologuard	Blood test
How often	Every 10 years	Yearly	Every 3 years	Interval still being defined
Where	Procedure with prep and sedation	At home	At home	Blood draw
Finds polyps?	Yes, and removes them	Detects some indirectly	Better than FIT, still limited	Weakest for polyps
Prevents cancer?	Yes, by removing polyps	Mainly detects	Mainly detects	Mainly detects
If positive	Definitive	Needs colonoscopy	Needs colonoscopy	Needs colonoscopy
Best for	Highest-yield screening; higher risk	Simple yearly average-risk screening	Non-invasive, more sensitive than FIT	Those who will not do other options

Which colorectal screening test should you get?

The right choice depends on your risk and, frankly, on what you will complete:

Higher risk (family history, prior polyps, symptoms): colonoscopy is the clear choice, and often at an earlier age and shorter interval.
Average risk, and willing to do a colonoscopy: it is the most complete option, catching and removing polyps in one step every 10 years.
Average risk, but you will not do a colonoscopy: a stool test (FIT yearly or Cologuard every 3 years) is far better than no screening, with the understanding that a positive result means a colonoscopy follows.
You have avoided screening altogether: a blood test is the newest and most convenient option, and while it is weaker at catching precancerous polyps, getting screened at all is a large improvement over nothing.

Fishtown Medicine

A 90-minute conversation with Dr. Ash. A written plan you can actually follow.

Start your intake

The theme is that the best test is the one you will complete. A perfect test you skip protects no one, while a good test you complete can prevent or catch a cancer early, when it is highly treatable.

How Fishtown Medicine approaches colorectal screening in Philadelphia

Guidance from the Clinic

Key Takeaways

Screening starts at age 45 for average-risk adults, lowered from 50 because colorectal cancer is rising in younger people; earlier with family history.
Colorectal cancer is highly preventable because it grows slowly from polyps that can be removed before they become cancer.
Colonoscopy is the most complete test, finding and removing polyps in one step every 10 years, and the clear choice for higher risk.
FIT, Cologuard, and blood tests are non-invasive alternatives, but any positive result still requires a colonoscopy.
The best test is the one you will complete - screening by some method matters far more than which one.
Fishtown Medicine helps you choose and refers colonoscopy to in-network gastroenterology in Philadelphia and South Jersey.

Advanced Cancer Screening - the broader early-detection picture, including Galleri and imaging
The Four Horsemen: The Diseases That End Most Lives - where cancer fits the longevity picture
Alcohol and Longevity - a modifiable colorectal cancer risk factor
Ultra-Processed Food - diet and colorectal risk
Preventive Care in Philadelphia - how screening fits a full prevention plan