Signs of colon cancer: 3 ways to recognize symptoms early.

Colorectal cancer (also known as colon cancer) is one of the leading causes of cancer death today . It can affect both men and women , regardless of race or lifestyle. Statistics show that over 90% of colorectal cancer cases occur in people over 50 years old .

The worrying thing is that in its early stages, colon cancer has almost no obvious symptoms . Many people only discover the disease when it has progressed to a severe stage, making treatment more difficult.

However, if you pay attention to your body and detect abnormal signs early , the chances of successful treatment are very high. Don't worry too much if you experience symptoms similar to colon cancer, as they sometimes appear in many other digestive diseases.

Most importantly, you should see a doctor as soon as you have any suspicious symptoms . Regular health checkups and colon cancer screenings are the "golden key" to early detection, before it's too late.

Part 1: Colon Cancer Symptoms: 5 Early Warning Signs You Need to Know

Sign 1: Pay attention if you see blood in your stool.

When you have a bowel movement, if you see blood in your stool , even just a small streak on the toilet paper, don't ignore it . This could be an early sign of colon cancer – a dangerous disease but one that can be treated effectively if detected early.

Here's what you need to know:

• Blood in the stool isn't always due to hemorrhoids. If you experience persistent, unexplained rectal bleeding that isn't related to an anal fissure or hemorrhoids, you should see a doctor immediately .

• The color of blood can vary depending on the location of the bleeding:

  • Bright red blood typically appears when bleeding occurs in the lower part of the colon or rectum.

  • Dark-colored blood or black stools can be a sign of bleeding in the upper part of the digestive tract, such as the stomach or small intestine.

• Unusual changes in stool odor are also a sign to watch out for. Stool with an unusually strong, unpleasant smell, especially if accompanied by changes in color or shape, is a time to see a doctor.

• Self-diagnosis is not recommended. Many people think it's just "mild hemorrhoids," but in reality, early-stage colon cancer often has symptoms very similar to common digestive problems.

Take proactive steps to get regular colon cancer screenings , especially if you are over 45 or have a family history of the disease. Early screening not only helps detect the disease at a treatable stage but also protects your gut health in the long term.

Sign 2: Monitor changes in bowel habits.

The body is always sending signals when something is wrong, and changes in bowel habits are one of the important signs you shouldn't ignore. Many people downplay "different bowel movements than usual," but in reality, this could be an early warning sign of colon cancer .

Here are some signs you should pay special attention to:

• Persistent or alternating diarrhea or constipation: If this condition occurs repeatedly over several days, especially without a clear cause, seek medical attention immediately.

• Abnormally small, thin, or long stools: People with colon cancer may notice their stools become longer, narrower, or flatter than usual.

• The feeling of still needing to defecate even after finishing: This is a common phenomenon in people with tumors obstructing bowel movements inside the colon .

• Changes in bowel movement frequency: Having fewer or more bowel movements than usual for several consecutive days can be a warning sign.

• Changes in stool consistency: Loose, sticky, or unusually textured stools should also be noted.

Note:

• These symptoms are not necessarily colon cancer . They can also appear in other digestive conditions such as irritable bowel syndrome (IBS) or transient digestive disorders.

• However, if the condition lasts longer than 3–4 days or recurs frequently, you should see a doctor for a check-up . Early diagnosis helps rule out the risk of cancer and allows for more effective treatment if there is an underlying condition.

Don't underestimate small changes in your body. Monitoring your bowel habits , noting any changes, and undergoing regular colon cancer screenings will help protect your digestive health and detect the disease at the earliest stage.

Symptom 3: Don't underestimate stomach pain and bloating.

Stomach pain or bloating are very common digestive symptoms, but if these symptoms persist or have no clear cause , you should be cautious . This could be an early warning sign of colon cancer , especially when accompanied by changes in bowel habits.

Signs to watch out for include:

• Dull or cramping abdominal pain: The pain may appear suddenly, spread throughout the abdomen, or be concentrated on one side.

• Persistent bloating and abdominal distension: If the feeling of fullness and discomfort doesn't subside despite dietary changes or digestive medication, you should see a doctor.

• Pelvic pain: In some cases, advanced-stage colon cancer can cause pain that radiates to the pelvis or lower back .

• Feeling bloated, indigestion, and feeling full quickly: These are early signs of gas buildup or obstruction in the colon.

Note:

• These symptoms do not necessarily mean you have colon cancer , as they are also common in people with inflammatory bowel disease, digestive disorders, or irritable bowel syndrome (IBS) .

• However, if the pain persists or is accompanied by weight loss, fatigue, or changes in stool , consult a gastroenterologist for examination and colon cancer screening .

In over 20 years of clinical practice, I've encountered many patients who came late simply because they thought "abdominal pain is a minor issue." In reality, early detection is always crucial in the treatment of colon cancer . Therefore, listen to your body – unexplained abdominal pain is a valid reason to see a doctor, not to wait.

Symptom 4: Unusual weight loss or loss of appetite

One of the subtle but worrying signs of colon cancer is unexplained changes in weight and appetite . Many people dismiss this, thinking they're just experiencing "poor appetite" or "losing weight because they're busy," but in reality, this could be a warning sign that their body is warning them of a serious underlying problem.

Here are some signs you should watch out for:

• Reduced appetite: You no longer find food as delicious as before, feel full quickly even when eating little, or no longer have an interest in foods you once loved.

• Unexplained weight loss: If you lose 4–5 kg or more in 6 months without changing your diet or exercise routine , this is an unusual sign that needs to be checked out.

• Fatigue, exhaustion, and loss of appetite: As a tumor in the colon grows, it can affect nutrient absorption, leading to a lack of energy and rapid weight loss.

• Changes in taste or mild nausea: Some people experience a persistent loss of appetite, bloating, or aversion to food.

Note:

• Small weight changes are normal, especially when you're stressed or experiencing lifestyle changes. However, rapid and unexplained weight loss should always be checked by a doctor.

• These symptoms can also occur in stomach, liver, or endocrine disorders , so early examination helps determine the exact cause and rule out colon cancer.

If you notice consistent weight loss despite eating normally , don't wait until you become severely ill to see a doctor. In fact, many colon cancer patients discover their disease thanks to unexplained weight loss. Regular screenings and weight monitoring are simple yet effective ways to protect your health.

Symptom 5: Persistent fatigue of unknown origin

Feeling tired and exhausted despite adequate rest is one of the signs your body is "speaking out" about a serious health problem. In many cases, this is an early symptom of colon cancer that patients often don't realize.

Here are some points you need to keep in mind:

• Persistent exhaustion: You feel weaker than usual, lack energy, or get tired quickly even with light work.

• Rest doesn't always bring recovery: Even with enough sleep and relaxation, the body still feels sluggish and lacking energy.

• Fatigue accompanied by other symptoms: If persistent fatigue is accompanied by digestive problems, abdominal pain, changes in bowel habits, or unexplained weight loss , you should see a doctor immediately.

• Medical cause: In people with colon cancer, fatigue is often due to occult anemia , which stems from microscopic bleeding in the colon that is not visible to the naked eye.

Note:

• Fatigue can stem from stress, lack of sleep, overwork, or a poor diet . However, if feelings of exhaustion persist without a clear reason , you should see a doctor for a general check-up and colon cancer screening .

In over 20 years of medical practice, I've noticed many people ignore signs of fatigue , assuming that rest alone will cure it. But with colon cancer, persistent fatigue is an early warning sign . Therefore, if you notice unusual health deterioration, get checked for peace of mind – or seek timely treatment while it's still early.

Part 2: When should you see a doctor? Signs and diagnosis of colon cancer

Step 1: When should you see a doctor?

Early detection of colon cancer increases the chances of successful treatment by up to 90%. Therefore, if you experience any of the unusual symptoms mentioned , don't wait – proactively schedule an appointment with your doctor immediately .

Here's what you need to do:

• Seek medical attention early if you have suspicious symptoms: Even if it's just blood in your stool, changes in bowel habits, abdominal pain, bloating, weight loss, or persistent fatigue , you should still get checked to rule out the risk of cancer.

• A doctor will help determine the exact cause: Through clinical examination, blood tests, colonoscopy, or imaging , the doctor can detect early signs of cancer or other diseases.

• Do not self-diagnose or self-treat at home. Many other medical conditions can cause symptoms similar to colon cancer , including:

  • Intestinal infections (gastroenteritis)

  • Irritable bowel syndrome (IBS)

  • Hemorrhoids or anal fissures
    These conditions are easily treatable, but if it's cancer, late detection will significantly reduce the effectiveness of treatment.

Don't wait until symptoms become severe to see a doctor. An early check-up can give you peace of mind , or save your gut health and even your life . If you are over 45 or have a family history of colon cancer, get regular screenings at least every 1–2 years .

Step 2: Discuss your medical history and risk factors for colon cancer with your doctor.

Understanding your personal risk factors is the first step in preventing and detecting colon cancer early. Being honest with your doctor helps them accurately assess your risk and develop a suitable screening plan for you.

Factors that may increase the risk of colon cancer include:

• Age: This is the leading risk factor. The majority of colon cancer cases occur in people over 50 , however, the disease is now trending towards affecting younger people.

• Personal or family history:

  • Have had a history of colon cancer or colon polyps .

  • Having a relative (father, mother, brother, sister) who has had this disease.

• Genetic factors: Certain genetic syndromes increase the risk of colon cancer, such as:

  • Familial adenomatous polyposis (FAP)

  • Lynch syndrome (Hereditary Nonpolyposis Colorectal Cancer – HNPCC)

• Sedentary lifestyle: Sitting for long periods and lack of exercise can reduce bowel motility and increase the accumulation of toxins in the colon .

• Unhealthy eating habits:

  • Eating too much fat, red meat, and processed foods .

  • Lack of fiber, green vegetables, and fresh fruit .

• Obesity or diabetes: These two conditions are associated with increased chronic inflammation and metabolic disorders , which increase the risk of cancer.

• Smoking and drinking alcohol: The toxins in cigarettes and alcohol can damage the lining of the colon and cause cellular changes over time.

• Race: Some studies suggest that African Americans have a higher risk of developing colon cancer compared to other population groups.

Even if you feel healthy, if you are in a high-risk group , talk to your doctor about a plan for regular screening . Lifestyle changes – eating a healthy diet, exercising regularly, limiting alcohol and tobacco – are simple but effective steps to significantly reduce your risk of colon cancer .

Step 3: Regular screening – the golden key to early detection.

The most effective way to prevent colon cancer or detect it in its early stages is to undergo regular screenings as recommended by your doctor , especially if you are 50 years of age or older or have high risk factors .

Common screening tests currently available include:

• Fecal occult blood test (FOBT):
  It helps detect microscopic blood in the stool – an early sign of lesions or tumors in the colon that are not visible to the naked eye.

• Stool DNA test:
  Testing for genetic markers related to cancer in stool samples helps detect polyps or precancerous lesions early , thereby preventing disease progression.

• Sigmoidoscopy:
  Doctors use an endoscope equipped with a camera and light to examine the rectum and lower part of the colon to look for polyps or abnormal growths.

• Complete colonoscopy:
  It is the gold standard method for colorectal cancer screening. Doctors can observe the entire colon, detect and remove polyps during the colonoscopy , and take tissue samples for biopsy if needed.

• Virtual colonoscopy or dual-contrast colonoscopy (DCBE):
  For those who cannot undergo endoscopy, this method uses X-ray or CT scan images to detect polyps or tumors on the colon wall.

Doctor's advice:

• Talk to your doctor to choose the screening method that best suits your age, health condition, and medical history.

• Early screening not only helps detect cancer in its earliest, most treatable stages , but also prevents cancer formation by removing polyps before they become malignant.

• Don't wait until you have symptoms to get checked – early-stage colon cancer often has no noticeable symptoms at all.

Step 4: Discuss treatment options with your doctor.

Receiving a positive colon cancer diagnosis is certainly a major shock – causing anxiety, confusion, and fear for anyone. However, it's important to remember that colon cancer is completely treatable if detected early , and there are now many methods to help control the disease, reduce symptoms, and extend lifespan .

Here are some commonly applied treatment approaches:

• Surgical removal of the tumor:

  • In early-stage colon cancer , doctors can remove the tumor during a colonoscopy , eliminating the need for open surgery.

  • If the disease progresses, surgery may be needed to remove the portion of the colon containing the tumor and reconnect the healthy part of the bowel.

• Chemotherapy:

  • Medications are used to kill cancer cells or prevent them from growing.

  • It is often indicated after surgery to reduce the risk of recurrence, or before surgery to shrink the tumor size.

• Radiation therapy:

  • Using high-energy rays to destroy cancer cells.

  • It is often combined with chemotherapy, especially in colorectal cancer or cases of local recurrence .

• Targeted therapy and immunotherapy:

  • Modern drugs help to precisely target cancer cells without damaging healthy tissue.

  • Suitable for patients with advanced or metastatic disease , helping to prolong survival time and improve quality of life.

• Psychological support and mental health care:

  • Facing cancer is not just a physical treatment journey, but also a mental battle .

  • Your doctor may refer you to mental health professionals, cancer support groups, or community organizations to help you and your family get through this difficult time.

  • Don't hesitate to share with your loved ones – their support and encouragement will make you much stronger.

Colorectal cancer is no longer a "death sentence" if detected early and treated properly. Have an open discussion with your doctor about treatment options , including benefits, side effects, and long-term care . Most importantly, maintaining a positive attitude and faith in your treatment plan is a valuable "medicine" that will help you overcome the disease.

Proactive prevention of colon cancer

If you are at high risk for colon cancer , it is crucial to discuss this with your doctor early on . Your doctor will help you develop a prevention and regular screening plan , and guide you on practical lifestyle changes to reduce your risk.

Here are some recommended measures:

• Regular screenings as directed by your doctor:

  • Start at age 50 , or earlier if you have genetic risk factors or a family history.

  • Numerous scientific studies have demonstrated that regular screening significantly reduces mortality rates from colon cancer by detecting precancerous polyps early.

• Maintain a healthy diet:

  • Eat plenty of green vegetables, fruits, whole grains, and fiber-rich foods .

  • Limit red meat, fried foods, saturated fats, and processed foods.

  • Drink enough water to support digestion and eliminate toxins.

• Increase physical activity:

  • Exercise for at least 150 minutes per week , including simple forms of activity such as walking, cycling, or yoga.

  • Regular physical activity helps reduce visceral fat accumulation, stabilize blood sugar, and decrease chronic inflammation – factors linked to cancer risk.

• Avoid tobacco and limit alcohol consumption.

  • Smoking and drinking alcohol increase the likelihood of damage to the cells lining the colon, which can then lead to mutations and cancer.

  • Quitting smoking and reducing alcohol consumption will significantly reduce the risk of recurrence or the formation of new tumors.

• Maintain a healthy weight and manage underlying medical conditions:

  • Obesity, diabetes, and high blood pressure are factors that contribute to an increased risk of colon cancer.

  • Controlling weight, maintaining a healthy diet, and undergoing regular health checkups help maintain a healthy digestive system in the long term.

Colon cancer doesn't happen suddenly—it develops silently over many years. Therefore, regular screenings and maintaining a healthy lifestyle are the most powerful "natural vaccines" to prevent the disease at its root . Proactively discuss screening options with your doctor and start making changes today —for your own health and the health of your family.

References

1. https://www.mayoclinic.org/diseases-conditions/colon-cancer/symptoms-causes/syc-20353669
2. https://www.cancer.org/latest-news/signs-and-symptoms-of-colon-cancer.html
3. https://www.unitypoint.org/livewell/article.aspx?id=a480319f-40e0-4e9d-b55c-bb896de04879
4. https://www.cancer.org/cancer/colon-rectal-cancer/detection-diagnosis-staging/signs-and-symptoms.html
5. http://www.mayoclinic.org/diseases-conditions/colon-cancer/symptoms-causes/dxc-20188239
6. https://www.cancer.gov/types/colorectal/screening-fact-sheet
7. https://www.cancer.org/cancer/colon-rectal-cancer/treating.html
8. https://www.mayoclinic.org/diseases-conditions/colon-cancer/diagnosis-treatment/drc-20353674

Translated by: Sidney Bailey Hoang .