Colorectal cancer develops in the colon or rectum and often begins as abnormal growths called polyps. Although it is one of the most common cancers, regular screening can detect precancerous changes before they become malignant. Understanding its symptoms, risk factors, screening methods, and treatment options can help individuals make informed decisions about prevention and care.
What Is Colorectal Cancer?
Colorectal cancer is a type of cancer that begins in the colon or rectum, which are parts of the large intestine.
The colon is responsible for absorbing water and electrolytes from digested food and forming stool. The rectum stores stool before it leaves the body through the anus.
Cancer develops when abnormal cells in these tissues grow uncontrollably and form malignant tumors.
Most colorectal cancers are adenocarcinomas, meaning they originate in glandular cells that produce mucus and other substances within the intestinal lining.
Many colorectal cancers begin as small growths called polyps. Although most polyps are not cancerous, certain types can gradually develop into cancer.
This progression often occurs over several years, creating an opportunity for screening tests to identify and remove precancerous growths.
Colorectal cancer is among the most common cancers diagnosed in the United States and remains a leading cause of cancer-related deaths.
According to the American Cancer Society’s 2026 estimates, approximately 158,850 new colorectal cancer cases and 55,230 related deaths are expected in the United States.
However, improvements in screening, diagnosis, and treatment have helped reduce colorectal cancer incidence and mortality among many older adults.
What Is the Difference Between Colon Cancer and Rectal Cancer?
Although colon and rectal cancers are frequently grouped together, their location can influence symptoms, staging, and treatment.
Colon cancer develops in the colon, which makes up most of the large intestine.
Rectal cancer begins in the rectum, the final portion of the large intestine located just above the anus.
Both cancers often develop from similar types of abnormal cells and share many risk factors.
However, rectal cancer treatment can be more complex because the rectum is located within the pelvis and lies close to surrounding organs and structures.
For example, radiation therapy is more commonly used in rectal cancer treatment than in colon cancer treatment.
Surgical approaches may also differ depending on the tumor’s location and whether normal bowel function can be preserved.
Why Is Colorectal Cancer Increasing Among Younger Adults?
Colorectal cancer has historically been associated with older age. However, diagnoses among younger adults have increased over recent decades.
This trend is often called early-onset colorectal cancer, referring to cases diagnosed before age 50.
According to the American Cancer Society’s 2026 colorectal cancer statistics, incidence rates increased by approximately 3% annually among adults aged 20 to 49 during the period from 2013 to 2022.
Researchers are still investigating why colorectal cancer is becoming more common in younger populations.
Potential contributing factors under investigation include obesity, dietary patterns, metabolic health, changes in the gut microbiome, and environmental exposures.
However, these factors do not fully explain the increase, and no single cause has been established.
Why Younger Adults Should Recognize the Symptoms
Younger patients may not immediately consider colorectal cancer when experiencing digestive symptoms.
Rectal bleeding, abdominal discomfort, or persistent changes in bowel habits may initially be attributed to hemorrhoids, irritable bowel syndrome, or other gastrointestinal conditions.
Although these conditions are much more common than cancer in younger adults, persistent symptoms should not be ignored.
People experiencing concerning symptoms should seek medical evaluation regardless of age or whether they have reached the recommended screening age.
How Does Colorectal Cancer Develop?
Many colorectal cancers develop through a process in which normal intestinal cells gradually acquire genetic changes.
These changes can cause cells to multiply abnormally and form polyps.
Over time, certain polyps may develop additional mutations and become malignant.
Understanding Colorectal Polyps
Polyps are abnormal growths that form along the inner lining of the colon or rectum.
Different types have different levels of cancer risk.
Adenomatous polyps: Also called adenomas, these growths can develop into cancer, particularly when they are large or have certain microscopic features.
Serrated polyps: Certain serrated lesions can also progress to colorectal cancer, sometimes through a different molecular pathway.
Hyperplastic polyps: Most small hyperplastic polyps, particularly those in the lower colon or rectum, have little or no malignant potential.
Not every polyp becomes cancerous.
However, removing precancerous polyps during colonoscopy can help prevent colorectal cancer from developing.
This ability to identify and remove abnormal growths is one reason colorectal cancer screening is particularly valuable.
What Are the Early Signs and Symptoms of Colorectal Cancer?
Colorectal cancer may not cause noticeable symptoms during its earliest stages.
As the disease develops, symptoms can vary depending on tumor location, size, and whether the cancer has affected surrounding tissues.
Common warning signs include:
- Persistent diarrhea or constipation
- Changes in stool frequency or consistency
- Blood in the stool or rectal bleeding
- Ongoing abdominal pain or cramping
- A feeling that the bowel does not empty completely
- Unexplained weight loss
- Persistent weakness or fatigue
- Iron-deficiency anemia without an obvious explanation
Some individuals may notice bright red blood, while others may have darker stools.
However, colorectal bleeding is not always visible.
A tumor may cause slow, ongoing blood loss that eventually contributes to anemia.
When Should You See a Doctor?
Persistent rectal bleeding, unexplained anemia, unintended weight loss, or a significant change in bowel habits should prompt medical evaluation.
These symptoms can occur with noncancerous conditions, but identifying their cause is important.
Sudden severe abdominal pain, persistent vomiting, inability to pass stool or gas, or heavy bleeding requires urgent medical attention.
What Causes Colorectal Cancer?
Colorectal cancer develops when cells accumulate changes that interfere with normal growth regulation.
These genetic changes may arise over time, result from inherited mutations, or be influenced by environmental and lifestyle factors.
In many cases, there is no single identifiable cause.
Researchers distinguish between risk factors that increase the likelihood of developing colorectal cancer and protective behaviors that may lower risk.
Understanding both can help guide preventive care.
Risk Factors for Colorectal Cancer
Some colorectal cancer risk factors cannot be changed, while others are related to potentially modifiable behaviors.
Age
The likelihood of developing colorectal cancer generally increases with age.
Although the disease remains more common among older adults, increasing diagnoses in younger populations emphasize the importance of recognizing symptoms at every age.
Family History
People with a close relative who has been diagnosed with colorectal cancer may have an increased risk.
The risk may be higher when multiple relatives are affected or when cancer develops at an unusually young age.
A family history can influence when screening should begin and which tests are recommended.
Inherited Genetic Syndromes
Certain inherited conditions significantly increase colorectal cancer risk.
Examples include:
- Lynch syndrome
- Familial adenomatous polyposis (FAP)
- MUTYH-associated polyposis
- Other hereditary colorectal cancer syndromes
People with these conditions may require specialized screening beginning much earlier than the general population.
Genetic counseling can help determine whether hereditary cancer testing is appropriate.
Inflammatory Bowel Disease
Long-standing inflammatory bowel disease, particularly ulcerative colitis and Crohn’s disease affecting the colon, can increase colorectal cancer risk.
Persistent intestinal inflammation may contribute to abnormal cellular changes over time.
Patients with inflammatory bowel disease may need more frequent colonoscopy surveillance.
It is important to distinguish inflammatory bowel disease from irritable bowel syndrome (IBS). IBS itself is not considered an established colorectal cancer risk factor.
Obesity and Physical Inactivity
Excess body weight and low physical activity levels are associated with increased colorectal cancer risk.
These factors may influence insulin regulation, inflammation, and metabolic processes.
Maintaining a healthy weight and engaging in regular physical activity may help reduce risk.
Smoking
Long-term tobacco use is associated with increased colorectal cancer risk and several other serious health conditions.
Quitting smoking provides benefits regardless of how long someone has smoked.
Alcohol Consumption
Alcohol consumption is associated with increased colorectal cancer risk, particularly at higher levels of intake.
Reducing alcohol consumption or avoiding it altogether may help lower risk.
Dietary Patterns
Frequent consumption of processed meat is associated with increased colorectal cancer risk.
Higher intake of red meat may also contribute to risk.
Meanwhile, dietary patterns that include whole grains, vegetables, fruits, and fiber-rich foods are generally associated with better overall health and may help reduce colorectal cancer risk.
No individual food can guarantee protection against cancer.
How Can You Reduce Your Risk of Colorectal Cancer?
Although some risk factors cannot be controlled, several practical measures may help reduce colorectal cancer risk.
Maintain a Balanced Diet
Choose a varied diet that includes:
- Vegetables and fruits
- Whole grains
- Beans and legumes
- Other fiber-rich foods
- Appropriate sources of protein
- Healthy dietary fats
Limiting processed meat and avoiding excessive alcohol intake may also support risk reduction.
Exercise Regularly
Physical activity supports metabolic health, cardiovascular function, and healthy body weight.
Adults should aim for an activity level appropriate to their health and physical abilities.
People with existing medical conditions should seek guidance before making major changes to their exercise routine.
Avoid Tobacco
Stopping tobacco use reduces exposure to carcinogenic substances and supports long-term health.
Smoking cessation programs and medical assistance may improve the chances of successfully quitting.
Maintain a Healthy Weight
Balanced nutrition and consistent physical activity can support weight management.
However, weight management recommendations should be individualized, particularly for people experiencing illness or nutritional difficulties.
Follow Recommended Screening Guidelines
Regular colorectal cancer screening is among the most effective preventive measures because certain screening methods can detect and remove precancerous polyps.
Screening should be based on age, medical history, family history, and individual risk.
When Should You Start Colorectal Cancer Screening?
The American Cancer Society’s updated 2026 guideline recommends that adults at average risk begin regular colorectal cancer screening at age 45.
Screening is generally recommended through age 75 for people in good health with a life expectancy greater than 10 years.
For adults aged 76 to 85, the decision should depend on overall health, previous screening history, life expectancy, and personal preferences.
Routine screening is not recommended for adults older than 85.
Who May Need Earlier Screening?
Some individuals require screening before age 45 or more frequent examinations.
These may include people with:
- A strong family history of colorectal cancer
- Certain inherited cancer syndromes
- A personal history of colorectal cancer or precancerous polyps
- Long-standing ulcerative colitis or Crohn’s disease affecting the colon
- Certain previous cancer treatments involving abdominal or pelvic radiation
Patients with concerning symptoms should receive diagnostic evaluation rather than waiting until their next routine screening appointment.
How Is Colorectal Cancer Screened and Diagnosed?
Several screening methods are available.
Some detect blood or abnormal molecular markers in stool. Others allow healthcare professionals to examine the colon and rectum directly.
It is important to distinguish routine screening, which is performed in people without symptoms, from diagnostic testing used to investigate suspected disease.
1. Colonoscopy
Colonoscopy is a procedure that allows a doctor to examine the inside of the colon and rectum.
A flexible tube equipped with a camera is inserted through the rectum to identify abnormalities.
If polyps are discovered, many can be removed during the same procedure.
Tissue samples may also be collected for laboratory analysis.
Colonoscopy generally requires bowel preparation and may involve sedation.
For average-risk individuals with normal results, screening colonoscopy is typically repeated every 10 years.
People with polyps or other risk factors may require more frequent examinations.
2. Fecal Immunochemical Test (FIT)
The fecal immunochemical test detects small amounts of human blood in stool that may not be visible.
It is a noninvasive screening option that can be completed at home.
For average-risk adults, FIT is generally performed annually.
However, not every colorectal cancer or precancerous polyp produces detectable bleeding.
A negative result therefore does not completely exclude colorectal cancer.
3. Guaiac-Based Fecal Occult Blood Test
The high-sensitivity guaiac-based fecal occult blood test detects blood in stool through a chemical reaction.
Depending on the testing method, patients may receive instructions about collecting samples and preparing for the test.
It is typically performed every year when used for screening.
Like FIT, it cannot directly identify the source of bleeding or remove polyps.
4. Stool DNA Testing
Stool DNA tests examine stool samples for molecular changes associated with colorectal cancer and certain precancerous growths.
Some tests also detect blood.
These tests can be completed without undergoing an invasive procedure.
Under current American Cancer Society recommendations, certain approved multitarget stool DNA tests are performed every three years for average-risk screening.
However, they do not detect every precancerous lesion or cancer.
5. CT Colonography
CT colonography, sometimes called virtual colonoscopy, uses computed tomography to create detailed images of the colon and rectum.
It typically requires bowel preparation and inflation of the colon with gas to obtain clear images.
For average-risk screening, it may be performed every five years.
Unlike conventional colonoscopy, CT colonography cannot remove polyps or obtain tissue samples.
If a suspicious finding is identified, a conventional colonoscopy is usually necessary.
6. Blood-Based Screening Tests
Newer blood-based tests can detect certain cancer-associated signals in the bloodstream.
These tests provide another screening option for eligible adults.
However, the American Cancer Society’s 2026 guideline does not consider them a preferred first-line screening method because they are less effective at detecting precancerous growths and some early-stage cancers.
They may be considered when a patient declines or has not completed preferred screening options.
Any positive result from a non-colonoscopy screening test requires timely follow-up with a colonoscopy.
How Is Colorectal Cancer Staged?
Once colorectal cancer has been diagnosed, healthcare professionals determine how far the disease has progressed.
This process is called staging.
Staging considers tumor size and depth, nearby lymph node involvement, and whether the cancer has spread to distant organs.
Stage 0
Abnormal malignant cells are confined to the innermost lining of the colon or rectum.
Treatment may involve removing the affected tissue.
Stage I
Cancer has grown into deeper layers of the intestinal wall but has not spread to nearby lymph nodes.
Surgery is commonly used for treatment.
Stage II
Cancer has grown through the intestinal wall or into nearby tissues but has not spread to regional lymph nodes.
Treatment generally involves surgery, with additional therapy considered according to individual risk factors.
Stage III
Cancer has spread to nearby lymph nodes but not distant organs.
Treatment commonly involves surgery and additional therapy, although the approach differs between colon and rectal cancer.
Stage IV
Cancer has spread to distant organs or tissues, commonly the liver or lungs.
Treatment may involve chemotherapy, targeted therapy, immunotherapy, surgery in selected cases, and supportive interventions.
The stage of colorectal cancer is an important factor in determining treatment options and prognosis.
What Are the Treatment Options for Colorectal Cancer?
Treatment depends on whether the cancer develops in the colon or rectum, its stage, molecular characteristics, and the patient’s overall condition.
Modern colorectal cancer treatment may involve several approaches rather than one standard procedure.
Surgery
Surgery is an important treatment for many localized colorectal cancers.
The procedure may involve removing the tumor, a portion of the affected intestine, and nearby lymph nodes.
When possible, surgeons reconnect the remaining healthy bowel.
In some cases, a temporary or permanent ostomy may be necessary.
An ostomy creates an opening through the abdominal wall that allows stool to pass into a collection bag.
However, not every colorectal cancer patient requires an ostomy.
The need for one depends on tumor location, surgical technique, and individual medical circumstances.
Chemotherapy
Chemotherapy uses medications to destroy cancer cells or prevent them from multiplying.
It may be given:
- After surgery to reduce the risk of recurrence
- Before surgery in selected situations
- Alongside other treatment methods
- As a primary treatment for advanced or metastatic disease
Chemotherapy recommendations vary according to cancer stage and other clinical factors.
Radiation Therapy
Radiation therapy uses high-energy radiation to damage cancer cells.
It is particularly important in selected cases of rectal cancer.
Radiation may be administered before surgery to help control the tumor or as part of a broader treatment plan.
It is used less frequently for colon cancer.
Targeted Therapy
Targeted therapies act against particular molecules or signaling pathways that contribute to cancer growth.
Some colorectal cancer treatments target pathways involving EGFR or VEGF, while others are directed at specific tumor mutations.
Biomarker testing helps determine whether certain targeted therapies may be appropriate.
Not every patient is eligible for the same medication.
Immunotherapy
Immunotherapy helps the immune system recognize and attack cancer cells.
Certain colorectal cancers have molecular characteristics that make them more responsive to immune checkpoint inhibitors.
For example, tumors with deficient mismatch repair (dMMR) or high microsatellite instability (MSI-H) may be candidates for particular immunotherapies.
These treatments can provide meaningful benefits for selected patients, but they are not appropriate for all colorectal cancers.
Clinical Trials
Clinical trials investigate new treatments, combinations of therapies, and strategies for improving cancer outcomes.
Patients may discuss clinical trial eligibility with their oncology team when considering available treatment options.
The Role of Supportive and Integrative Care
Colorectal cancer and its treatment can affect digestion, nutrition, energy levels, emotional health, and quality of life.
Supportive care addresses these needs alongside cancer-directed treatment.
Nutritional Support
Patients may experience changes in bowel function, appetite, digestion, or nutrient absorption during treatment.
A registered dietitian can help create a meal plan that supports adequate nutrition while accounting for treatment-related symptoms.
Dietary recommendations may differ before and after surgery, during chemotherapy, or when a patient has an ostomy.
Managing Treatment Side Effects
Chemotherapy, radiation therapy, and surgery may cause fatigue, nausea, bowel changes, pain, or other symptoms.
Appropriate medication, rehabilitation, and symptom management can improve comfort and daily functioning.
Emotional and Psychological Well-Being
A colorectal cancer diagnosis can create anxiety, uncertainty, and emotional distress.
Counseling, support groups, and family involvement may help patients manage the psychological challenges of treatment.
Complementary Supportive Therapies
Some patients explore relaxation exercises, gentle physical activity, mindfulness, or other complementary approaches.
These practices may help with certain symptoms and quality-of-life concerns when medically appropriate.
However, complementary therapies should not replace evidence-based cancer treatment.
Patients should discuss supplements and other interventions with their oncology team because some products may interfere with prescribed medications.
Why Early Detection Matters
Colorectal cancer is unusual among common cancers because screening can both detect cancer and help prevent it.
Removing precancerous polyps can interrupt the progression toward malignancy.
Early-stage colorectal cancer also generally offers more treatment opportunities than disease that has spread to distant organs.
However, routine screening is only one part of prevention.
Recognizing persistent symptoms, discussing family history, and seeking medical evaluation when appropriate are equally important.
The rise in colorectal cancer among younger adults reinforces the need to take concerning digestive symptoms seriously, even before the usual screening age.
The Bottom Line
Colorectal cancer develops in the colon or rectum and often begins as a precancerous polyp.
Although it remains a major cause of cancer-related illness and death, screening and early detection can significantly improve opportunities for prevention and treatment.
Risk factors include age, family history, inherited genetic conditions, inflammatory bowel disease, tobacco use, excess body weight, alcohol consumption, and certain dietary patterns.
Current screening guidelines recommend beginning at age 45 for most adults at average risk, while people with elevated risk may need earlier or more frequent testing.
Treatment options continue to evolve and may include surgery, chemotherapy, radiation therapy, targeted therapy, and immunotherapy.
Understanding these options helps patients and families make informed decisions about colorectal cancer prevention, diagnosis, and care.
Explore Personalized Colorectal Cancer Care
Every colorectal cancer diagnosis is different, and treatment planning should consider the patient’s cancer stage, overall health, medical history, and individual needs.
At New Hope Unlimited, our integrative approach to cancer care emphasizes personalized treatment planning, supportive care, and quality of life. Contact our team to learn more about our cancer treatment programs and available supportive care options.
FAQs
What is colorectal cancer?
Colorectal cancer is cancer that begins in the colon or rectum. Most cases are adenocarcinomas that develop from glandular cells in the intestinal lining. Many colorectal cancers begin as precancerous polyps that gradually develop abnormal cellular changes.
What are the early warning signs of colorectal cancer?
Early colorectal cancer may not cause symptoms. Possible warning signs include rectal bleeding, persistent changes in bowel habits, abdominal discomfort, unexplained weight loss, and iron-deficiency anemia. Persistent or unexplained symptoms should be evaluated by a healthcare professional.
At what age should colorectal cancer screening begin?
The American Cancer Society recommends regular colorectal cancer screening beginning at age 45 for adults at average risk. Individuals with a strong family history, inflammatory bowel disease, or certain inherited genetic conditions may require earlier screening.
Can colorectal cancer develop in people younger than 45?
Yes. Colorectal cancer can occur in younger adults, and diagnoses among people younger than 50 have increased in recent decades. Concerning symptoms should be medically evaluated regardless of age, even when someone has not reached the recommended routine screening age.
Is colorectal cancer hereditary?
Some colorectal cancers are linked to inherited genetic conditions, including Lynch syndrome and familial adenomatous polyposis. However, most cases are not directly attributable to a known inherited syndrome. Family history can help determine whether genetic counseling or earlier screening is appropriate.
Does irritable bowel syndrome increase colorectal cancer risk?
Irritable bowel syndrome (IBS) is not an established risk factor for colorectal cancer. However, inflammatory bowel disease (IBD), including ulcerative colitis and Crohn’s disease affecting the colon, can increase risk. The two conditions are different and should not be confused.
Can a colonoscopy prevent colorectal cancer?
Colonoscopy can help prevent colorectal cancer by identifying and removing certain precancerous polyps before they become malignant. It can also detect existing cancers, often before symptoms develop. However, no screening test prevents or detects every case.
What happens if a stool test for colorectal cancer is positive?
A positive stool-based screening result does not automatically mean cancer is present. It indicates that further evaluation is necessary. A timely colonoscopy is generally recommended to examine the colon and rectum and identify the cause of the abnormal result.
What are the main treatments for colorectal cancer?
Treatment may involve surgery, chemotherapy, radiation therapy, targeted therapy, or immunotherapy. The recommended approach depends on whether the cancer is in the colon or rectum, its stage, molecular characteristics, and the patient’s overall health.
Can colorectal cancer be cured?
Colorectal cancer can sometimes be cured, particularly when diagnosed at an early stage and treated successfully. Some patients with more advanced disease may also achieve long-term disease control. However, outcomes depend on the cancer’s characteristics, treatment response, and individual medical factors.
Does every colorectal cancer patient need a colostomy bag?
No. Many patients undergo surgery without requiring a permanent colostomy. Whether a temporary or permanent ostomy is needed depends on the tumor’s location, the surgical procedure, and whether normal bowel connections can be preserved.
Can immunotherapy treat colorectal cancer?
Immunotherapy may be effective for selected colorectal cancers with particular molecular characteristics, including mismatch repair deficiency or high microsatellite instability. Biomarker testing can help determine whether a patient may benefit from this treatment.