Everything to Know About Colorectal Cancer

Colorectal Cancer (CRC) is the third most diagnosed cancer in the U.S. It is also the second deadliest for both men and women. The good news is, it is preventable. The timeline for most CRC begins with removable polyps, making CRC one of the most preventable cancers. 

The most important point in this resource is screening the U.S. The Preventive Services Task Force and the American Cancer Society both recommend that average-risk adults initiate screening at the age of 45^[1].

If found early, a patient’s survival rate is about 91.3% over five years. This is very different from the 16.9% survival rate for CRC when it spreads to other organs.

What Is Colorectal Cancer?

Cancer develops in the large intestine when cells grow uncontrollably on the lining of the colon or rectum. “Colorectal” combines both of these; in the rest of the world “, bowel cancer” is a more common term.

Colon and rectum

This is the last part of the large intestine that absorbs water and electrolytes to form stool. This is the last part of the large intestine. The rectum is the final several inches of the large intestine where stool is temporarily stored before the body excretes it. 

Cancer begins along this large intestine and can grow at any location within. This will dictate how it behaves as well as the approach used to treat it.

How colorectal Cancer begins

Most colorectal cancers develop through precancerous lesions, although not all follow the traditional adenoma-to-carcinoma sequence.This sequence roughly takes at least 10 years before a cancer diagnosis, with the development of an adenomatous polyp^[2] .

During this time, the polyp gets mutations. These happen slowly, making the polyp easy to spot and remove with a colonoscopy. 

Most cases of colorectal cancer do not develop via this polyp sequence.

Types of colorectal Cancer.

About 95% to 98% of cancers^[3] of the colon and rectum are adenocarcinomas. The others are less common. These include neuroendocrine tumours and squamous carcinomas.

Some GISTs, lymphomas, and adenosquamous carcinomas occur. Special treatment is needed for these diagnoses, and they are not part of the focus of general screening advice.

How Common Is Colorectal Cancer? (Epidemiology & Statistics)

Colorectal cancer is the third most common cancer in the U.S. It’s also the second deadliest. Among adults younger than 50 in the U.S., colorectal cancer is now the leading cause of cancer-related death.

According to the American Cancer Society, they predict 158,850 new cases and 55,230 deaths due to colorectal Cancer by the year 2026.

U.S. incidence and mortality

The ACS’s 2026 report predicts 158,850 new cases of colon and rectal cancer. This includes 108,860 colon and 49,990 rectal incidents. Sadly, it also estimates 55,230 deaths. Almost a third of these deaths will be in people under 65. 

The lifetime risk for men is roughly 1 in 24 and 1 in 26 for women (check the current ACS Colorectal Cancer Facts & Figures report^[5], as the exact numbers and order shift sometimes with each report).

The incidence dropped by about 45%. This change is due to fewer lifestyle-related risk factors and more screenings in recent decades.

Global statistics

In 2022, colorectal cancer ranked as the third most common and the second deadliest cancer worldwide. There were over 1.93 million new cases and 904,000 deaths. This accounted for 9.6% of all cancer cases and 9.3% of cancer deaths. 

U.S. government sources generally round the above figures for global cancer deaths to around 903,900. This difference is small, but we should note the ambiguity in these figures. There could be data discrepancies.

Historical trends

CRC cases have decreased since mass screenings and the removal of polyps occurred in adults aged 50 and older in 1986.

After 2013, the last decade has seen a drop of 2.5% in new CRC cases in the population aged 65+ due to increased life expectancy.

There has been a 3% increase in incidence of CRC in the 20- to 49-year-old population^[6], and a 0.4% increase in incidence in the 50- to 64-year-old population.

In 1995, 27% of the total number of cases diagnosed were in individuals less than 65 years old. This has since grown to 45% in recent years.

The rise of early-onset colorectal Cancer.

The most pressing issue today is early-onset colorectal Cancer (EOCRC). Rising rates of EOCRC before age 50 now make it the leading cause of cancer death for ages 0-50. 

Current research predicts that by 2030, approximately 11% of colon cancers^[7] and 23% of rectal cancers will occur before age 50.

Just over 16% of early-onset EOCRC cases have an inherited cancer gene; the remaining cases are not attributed to an inherited risk. 

Researchers are studying why early-onset EOCRC cases are rising. 

The main theories for early-onset EOCRC cases include poor health habits.

These habits are linked to:

Research institutions say that studies on early-onset EOCRC cases are ongoing. However, this is not a well-established research area.

What Causes Colorectal Cancer? Risk Factors Explained

The majority of cases of colorectal Cancer are associated with risk factors that can be changed. Several modifiable factors are associated with colorectal cancer risk, although many cases also occur in people without identifiable modifiable risk factors.

Non-modifiable risk factors

We will cover key risk factors for CRC.

These include:

Most diagnosed cases occur between the ages of 65 and 74; however, this is shifting towards a younger population.

Inherited syndromes.

Lynch Syndrome makes up about 3-5% of colorectal cancer cases. The lifetime risk of CRC ranges from 10% to 80%. This risk varies based on the specific gene involved: MLH1, MSH2, MSH6, PMS2, or EPCAM. 

Familial adenomatous polyposis (FAP) is caused by mutations in the APC gene. This leads to nearly a 100% lifetime risk of colorectal cancer (CRC), often occurring before age 40.

Most people with FAP will need colon surgery. FAP is a rare inherited syndrome and accounts for a small proportion of colorectal cancers^[8].

Inflammatory bowel disease.

Ulcerative colitis and Crohn’s colitis increase CRC risk by two to three times. The longer and more severe the disease, the higher the risk (PMC10452690).

Type 2 diabetes

Adults with type 2 diabetes face a meta-analysis-estimated relative risk of about 1.37 for developing colorectal Cancer.

Racial and ethnic disparities.

In the U.S., Black Americans are about 20% more likely to be diagnosed with colorectal cancer. They also face a 30% higher chance of dying from it compared to White Americans. American Indian and Alaska Native populations have some of the highest rates of colorectal cancer cases and deaths in the world. 

The main reason for these disparities is socioeconomic factors. They affect access to preventive screening and health care. 

Modifiable risk factors

Excess body weight, low physical activity, high processed meat diets, lack of fiber, smoking, and too much alcohol can lead to large intestine cancer. They should not be taken lightly, since they can be modified.

Red and processed meat.

Excess body weight, being inactive, and eating unhealthy diets high in red and processed meat can raise your risk of colorectal cancer. Low fiber intake, smoking, and drinking too much also contribute to this risk. Still, they can all be altered or reversed.

The World Health Organization’s International Agency for Research on Cancer (IARC) ranks processed meat as a Group 1 carcinogen. This means it is “carcinogenic to humans.” It ranks red meat as Group 2A, or “probably carcinogenic to humans”. 

The classifications focused mainly on evidence for colorectal cancer. They were made in 2015 (WHO/IARC). The IARC did a pooled analysis of studies.

They found that eating 50 grams of processed meat, like two slices of bacon or one hot dog, raises the risk of colorectal cancer by about 18%. 

A 2025 meta-analysis of 60 long-term studies found similar results. It reported that red meat raised the risk of colorectal cancer by about 15%. Processed meat increased the risk by about 21%. (PMC12181564).

Alcohol, smoking, weight, inactivity.

The ACS reports that smoking causes 19% of cancer cases in the U.S. Obesity contributes about 8%, while alcohol accounts for around 5%^[6]. These percentages apply to all types of cancer. 

Colorectal cancer risk, on the other hand, decreases as a person’s weight decreases and as they partake in more physical activity and consume less alcohol. The dose-response relationship also applies to this case.

Colorectal Cancer Symptoms and Warning Signs

Most early-stage colorectal cancers and the polyps which precede them have virtually no symptoms. In the absence of obvious symptoms, screening is more important than symptom evaluation.

The first signs may include:

Red-flag symptoms that warrant prompt evaluation.

You should see a doctor right away if you have:

In 2026, data from the American College of Surgeons showed a strong link between rectal bleeding in patients under 50 and colon cancer. If you have symptoms before the age for routine colorectal screenings, see a doctor. Discuss whether you need a colonoscopy.

Symptoms don’t equal Cancer.

All of these signs can be symptoms of diseases with varying severity. It’s important not to assume the worst. If these signs are identified and evaluated, a doctor is able to quickly diagnose the cause of the symptoms. Most people who display these symptoms do not have Cancer.

At what age should screening start?

Average-risk individuals should begin colorectal cancer screenings at 45 years old. Screening for Cancer permits doctors to identify and remove precancerous polyps before they become cancerous. There are not many cancer prevention tools that do not merely identify Cancer.

Screening earlier for higher-risk people.

The U.S. Preventive Services Task Force (2021) and the American Cancer Society (2018, reaffirmed 2026) recommend that average-risk adults start screening at age 45. 

The USPSTF recommends colorectal cancer screening for adults aged 50 to 75 years with a Grade A recommendation, and for adults aged 45 to 49 years with a Grade B recommendation. For ages 76-85, they recommend screening on a case-by-case basis, based on health and screening history (USPSTF, 2021)^[1]. 

The ACS recommends screening until age 75 if life expectancy is over 10 years. For ages 76 to 85, screening should be done case by case. Screening is generally not recommended after age 85.

The screening tests, compared

If you have a family history of colorectal cancer, heritable polyps, young-onset colorectal cancer, Lynch syndrome, or Familial Adenomatous Polyposis (FAP), talk to your doctor. You may need to start screening earlier and more often. 

This includes starting screening at 40 years old or younger, or 10 years before the age at which a family member was diagnosed. A genetic counsellor gives information and finds families with a strong cancer history. These families may have a higher risk.

Screening methods, compared

There are two main types of screening tests:

New blood tests are also available.

What about the blood test?

The FDA approved Guardant Health’s Shield test in 2024, making it the first blood test approved as a primary colorectal cancer screening for adults 45 and older with an average risk and a testing frequency of every three years. 

Sensitivity for Shield in the ECLIPSE study reported^[9] by Chung et al., 2024, in the New England Journal of Medicine was 83.1% for advanced colorectal Cancer at around 90% specificity for advanced neoplasia, and only around 13% sensitivity for advanced precancerous polyps, Because its sensitivity for advanced adenomas is limited, a negative Shield result does not provide the same opportunity for detecting and removing precancerous lesions as colonoscopy. 

The ACS includes blood tests among their criteria, although these are not preferred methods. The USPSTF’s 2021 report^[1] does not include blood tests at all.

This is how it really is: convenient and much better than the alternative of skipping screenings, but likely to miss precancer, and a positive result would still warrant a colonoscopy.

How Is Colorectal Cancer Diagnosed and Staged?

Colonoscopy and biopsy are necessary to confirm colorectal Cancer. After Cancer is confirmed, blood tests, imaging, and molecular testing are used to determine the stage of the Cancer and effective treatments.

Diagnostic workup.

When concerns about colorectal Cancer arise, a colonoscopy with biopsy is the gold standard for tumour evaluation and tissue sampling. A pathologist examines the sampled tissue to verify Cancer. 

In addition, evaluation of distant organ involvement is important for better understanding the Cancer and the extent of disease.

This is accomplished through computed tomography (CT) of the chest, abdomen and pelvis. For some cancers, magnetic resonance imaging (MRI) may be useful. 

Other imaging studies such as positron emission tomography (PET) may also be ordered. At the time of cancer diagnosis, a blood test to measure carcinoembryonic antigen (CEA) levels may be ordered and repeated to evaluate treatment effectiveness.

Measurement of CEA levels is also not useful in the screening setting due to lack of sensitivity.

Biomarker / molecular testing.

Recognizing the biology of a colorectal cancer (CRC) tumour helps guide treatment. Traditionally, the size and location of the tumour determined treatment. 

The NCCN recommends that all patients undergo MSI/MMR testing. MSI/MMR testing helps determine patients at risk for Lynch Syndrome, provides prognostic information and may also determine whether a patient is eligible for Immune therapy. 

MSI-high tumours (or deficient in MMR (dMMR) tumours) comprise approximately 4-5% of metastatic colorectal cancers^[10].

When dealing with Stage IV or metastatic cases, additional testing of KRAS, NRAS, BRAF and HER2 is recommended.

ctDNA, or cell-free DNA fragments from a tumour, is tumour DNA that sheds into the bloodstream. Like cfDNA, ctDNA can be measured in the blood. 

ctDNA is being researched for detection of residual disease after surgical removal of the primary tumour and for guidance of adjuvant treatment. Because this is an area of active, ongoing research, there are very few standard practices.

Understanding the stages (0–IV).

The TNM system is used to classify colorectal cancers and similar cancers, based on how deep the Cancer has grown into the bowel (T), if the Cancer is in the lymph nodes (N), and if the Cancer has spread to other organs (M).

The NCI’s SEER database categorizes survival statistics differently from how TNM stages are described. The SEER database groups survival statistics into one of the following categories: localized (stages 0-1), regional (stage III, with spread to nearby lymph nodes or other structures), and distant (stage IV).

How Is Colorectal Cancer Treated?

Colorectal cancer treatment takes many factors into account, such as the Cancer’s stage and location. More and more, oncologists are also taking into account the Cancer’s molecular profile.

There are various approaches to treating colorectal Cancer, and a patient’s health care team may use a combination of the following.

Surgery

Surgery is the mainstay of treatment for the various stages of colorectal Cancer. For early stages (0 to I) of Cancer of the colon, complete removal may be performed during a colonoscopy.

For more locally advanced colon cancers (stage II and III), a colectomy, along with lymph node removal and removal of the adjacent mesocolon, is performed.

This operation is usually curative. For cancers of the rectum, the surgery is more complex, and in addition to removal of the Cancer and some normal tissue, adjacent organs may also be removed.

A permanent or temporary colostomy may be required.

Chemotherapy

Chemotherapy regimens based on fluoropyrimidines, platinum-based agents, and other chemotherapy medicines may be used to treat colorectal cancer. The specific regimen depends on the cancer stage, location, molecular characteristics, and the patient’s overall health.

They are given post-operatively to patients with stage III cancers and to select patients with stage II cancers.

Fluoropyrimidine-based chemotherapy is commonly used in colorectal cancer treatment. Luporal (Tegafur/Uracil) is an oral chemotherapy option used in the treatment of cancers of the colon and rectum.

Radiation therapy

Radiation plays a role mainly in the treatment of cancers of the distal colon and rectum. Neoadjuvant chemoradiation is used to downsize tumour bulk.

Recently, total neoadjuvant therapy has gained popularity, whereby radiation and chemotherapy are administered in that order to downsize the tumour before resection.

Radiation is rarely, if ever, used for treatment of cancers of the proximal colon.

Targeted therapy

Several targeted drugs are now matched to a tumour’s specific mutations. Targeted therapies may be used when the tumour has specific molecular characteristics. For example, EGFR-targeted therapy may be considered for selected RAS wild-type tumours, while other targeted treatments may be used for tumours with specific BRAF, KRAS, or HER2 alterations.

Anti-VEGF therapy (VEGF-targeted therapy) is often added to chemotherapy backbones in first-line metastatic treatment. Tumours with a BRAF V600E mutation may be treated with BRAF-targeted therapy.

For patients with advanced colorectal cancer, Tipanat 15 mg (Trifluridine/Tipiracil) and Tipanat 20 mg (Trifluridine/Tipiracil) may be used as later-line treatment options when the disease has progressed following previous therapies.

Immunotherapy

Immunotherapy can be an important treatment option for patients with MSI-high or dMMR metastatic colorectal cancer. The choice of immunotherapy depends on the tumour’s molecular characteristics and the patient’s clinical situation.^[12].

Immunotherapy, and in particular immune checkpoint inhibitor therapy, has the potential to provide durable responses in patients with mCRC, especially as compared to traditional chemotherapy.

Various clinical trials have been initiated to study the combination of chemotherapy and immunotherapy for patients with Stage III dMMR tumor cancers.

Recent advances (frame as evolving).

There are several new approaches to colorectal cancer treatment. Some oncologists are beginning to use tumour mutational burden and ctDNA to help decide which patients would benefit from adjuvant chemotherapy following surgery. 

Other oncologists are beginning to use “watch and wait” strategies for selecting patients with good responses to neoadjuvant therapy for rectal Cancer.

Still other patients are benefiting from recently approved and FDA-labeled therapies directed at molecularly defined subgroups.

Colorectal Cancer Prevention and Risk Reduction

Screening and polyp removal

Of all the strategies available for the prevention of colorectal Cancer, screening is by far the most effective because it can prevent the progression of colonic polyps to colon cancer through the removal of polyps by colonoscopy.

Diet and lifestyle

Beyond screening, a cluster of lifestyle habits meaningfully lowers risk: eating more fiber, whole grains, fruits, and vegetables; limiting red and processed meat; maintaining a healthy weight; staying physically active; limiting alcohol; and not smoking. 

None of these guarantee protection, but together they address a large share of the modifiable risk discussed earlier in this guide.

Colorectal Cancer Survival Rates and Life After Treatment

Survival by stage

Surveillance after colorectal cancer treatment includes regular colonoscopies, blood tests, and scans. Surveillance is designed to discover the return of colorectal Cancer or the growth of polyps. The surveillance schedule is individualized based on the risk of the Cancer returning. 

The National Comprehensive Cancer Network (NCCN) and the American Society of Clinical Oncology (ASCO) have recommendations for the surveillance of patients that have been synthesized to create guidelines for individualized surveillance. These recommendations should be discussed with your health care team.

Follow-up and surveillance

In 2025, there were over 1.4 million colorectal cancer survivors in the U.S. (Siegel et al., 2026). There are unique concerns for this population, such as coping with an ileostomy or colostomy and the physical changes from chemotherapy. 

The survivorship support structures that are available should be utilized to the fullest extent. They are able to provide both physical and psychological support. 

They are often able to refer clients to other services or support structures. Survivorship support structures should be integrated into the oncology support structures.

Quality of life and survivorship

By January of 2025, approximately 1.4 million people^[4] in the U.S. were cancer survivors. Considering the survivorship of colorectal Cancer has its own challenges. 

This may include coping with the physical changes caused by colorectal Cancer, such as adaptation to an ostomy, changes in bowel function and continuous nerve changes (neuropathy) caused by the Cancer or its treatment. Surviving Cancer may also take an emotional toll on a person.

Several resources are available to help assist with these challenges. 

The resources include, but are not limited to, cancer support organizations, patient navigators, and survivorship clinics. Speaking with your health care team about these resources may be beneficial.

The Bottom Line

Many people don’t know that colorectal Cancer is one of the few cancers for which a cancer screening test can actually prevent Cancer, versus just identifying Cancer. Starting at age 45, it is recommended that all people should be screened for colorectal Cancer.

If you have a family history of colorectal Cancer, you should be screened prior to age 45. Symptoms of colorectal Cancer may include a change in bowel habits, such as constipation or diarrhea, blood in your stool, and/or unintended weight loss. 

If you experience any of these symptoms, you should see your doctor even if you are not of screening age. Often, there are no symptoms if Cancer is present. Treatment for colorectal Cancer is continuously improving. 

Survival from colorectal Cancer is dependent on many factors, such as the stage of the Cancer, the location of the Cancer, and the biology of the Cancer. Your doctor can explain the risks to you based on your personal and family history.

FAQ

This article is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your doctor about your own risk, symptoms, or treatment plan.