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Colon cancer is a type of cancer that often starts in the large intestine. Suspicious symptoms include blood in the stool, changes in bowel habits such as alternating diarrhea and constipation, fatigue, and weight loss. Regular screening for colon cancer or early detection of abnormalities can significantly reduce the mortality rate from this disease.
What is Colon Cancer?
Colon cancer occurs when cancer cells grow in the large intestine. In its early stages, it often shows no symptoms. If the cancer starts in the rectum, colon cancer and rectal cancer can occur together. Currently, colon cancer is becoming more common in Thailand. Therefore, individuals with suspected colon cancer symptoms or those who notice changes in their bowel habits should consult a doctor. If left untreated, colon cancer can spread to other parts of the body and be fatal.
Symptoms of Colon Cancer
Suspicious Signs and Symptoms That May Indicate Colon Cancer:
- Changes in bowel habits: Such as persistent diarrhea and/or constipation, or still feeling the urge to defecate immediately after a bowel movement.
- Rectal bleeding or blood in the stool.
- Persistent abdominal discomfort: Such as cramping or gas.
- Feeling of incomplete bowel emptying.
- Weakness or fatigue.
- Unexplained weight loss.
Symptoms of Colon Cancer at Each Stage
The earliest stage of colorectal cancer is called Stage 0 (carcinoma in situ) and is further divided into Stages 1-4. Earlier stages indicate less cancer spread, while later stages, such as Stage 4, mean the cancer has spread more extensively.
Stage 0:
The cancer is in its earliest stage. At this stage, the cancer is confined to the inner lining of the colon and has not grown beyond the mucosal layer of the large intestine or rectum.
Stage 1:
The cancer has grown more, but is still within the colon lining. It has not spread to nearby lymph nodes or other locations.
Stage 2:
The cancer has grown to the outermost layers of the colon or rectum, or has grown through the wall of the large intestine or rectum, invading nearby tissues or organs, but has not spread to nearby lymph nodes or other locations.
Stage 3:
The cancer has grown through the wall of the large intestine or rectum and is attached to or growing into other nearby tissues or organs. It has spread to nearby lymph nodes but has not spread to distant organs.
Stage 4:
The cancer has spread to distant lymph nodes or may have spread to distant organs.
| Stage 1 | Stage 2 | Stage 3 | Stage 4 |
|---|---|---|---|
|
Constipation |
Constipation |
Feeling weak |
Yellow skin/eyes |
|
Diarrhea |
Diarrhea |
Unexplained fatigue |
Swelling in hands and feet |
|
Changes in stool shape and color |
Changes in stool shape and color |
Weight loss |
Difficulty breathing |
|
Blood in stool |
Blood in stool |
Changes in stool lasting more than 1 month |
Chronic headache |
|
Rectal bleeding |
Rectal bleeding |
Feeling of abdominal fullness/incomplete bowel emptying |
Blurred vision |
|
Bloating, excessive gas |
Bloating, excessive gas |
Vomiting |
Easy bone fractures |
|
Abdominal pain, cramping |
Abdominal pain, cramping |
What Does Colon Cancer Stool Look Like?
The appearance of stool in individuals with colon cancer is difficult to definitively describe. Cancer can cause narrowing of the large intestine or rectum, obstructing the passage of waste or interfering with nutrient and electrolyte absorption. This can lead to constipation that doesn’t improve with medication for more than 2-3 days or bowel obstruction.
Stool may be hard and small like pebbles, resulting from water absorption due to the stool remaining in the intestines for too long. Alternatively, stool may be thin and narrow if it is squeezed through an obstruction in the large intestine or rectum.
Symptoms of Advanced-Stage Colon Cancer
Individuals with metastatic colon cancer may experience the following symptoms:
- Dark blood in stool/black stool
- Constipation and/or diarrhea
- Long, thin, pencil-like stools
- Fatigue/weakness
- Abdominal pain, fullness, bloating
- Unexplained weight loss
- Nausea and vomiting
When cancer spreads, other symptoms may appear depending on where the tumor forms. Cancer can spread to the liver, lungs, and peritoneum. If cancer spread is found in the lungs, it can cause difficulty breathing and shortness of breath. If found in the liver, it can lead to nausea and jaundice.
What Causes Colon Cancer?
Several factors are associated with an increased risk of colon cancer.
Currently, there is no single definitive cause of colon cancer, but several factors may increase the risk:
Inflammatory bowel diseases:
Such as Crohn’s disease or ulcerative colitis.
Family history:
Of colorectal cancer or polyps in the large intestine and rectum.
Lack of regular physical activity.
Low intake of fruits and vegetables:
Consuming fruits and vegetables can help reduce the risk factors for colon cancer.
Diet low in fiber and high in fat:
Especially a diet high in processed meats.
Overweight or obesity.
Alcohol consumption or smoking.
Diagnosing Colon Cancer
Colon Cancer Screening
Doctors recommend regular colon cancer screening for healthy individuals without any signs or symptoms to look for signs of colorectal cancer or non-cancerous polyps. Detecting colon cancer in its early stages offers the highest chance of cure and reduces the risk of death from the disease.
Generally, individuals at average risk for colon cancer are advised to begin screening at the age of around 45. However, those with increased risk, such as a family history of colon cancer or African-American ethnicity, should consider earlier screening.
There are various screening methods, such as colonoscopy. If a doctor finds polyps during the examination, they can be removed before they become cancerous.
Diagnosing Colon Cancer
If symptoms suggest potential colon cancer, your doctor may recommend the following tests:
1. Colonoscopy
This involves using a long, flexible, slender tube attached to a video camera and monitor to examine the entire large intestine and rectum. If suspicious areas are found, the doctor can collect tissue samples (biopsy) for analysis and remove polyps.
2. Blood Tests
No single blood test can definitively diagnose colon cancer. However, doctors may order blood tests to check kidney and liver function, and for abnormal substances produced by colon cancer, such as carcinoembryonic antigen (CEA).
3. Other Tests:
Doctors may order additional imaging tests such as Computerized Tomography (CT) scans or Magnetic Resonance Imaging (MRI).
Colon Cancer Treatment
Can Colon Cancer Be Cured?
Most colon cancer treatments involve surgical removal of the cancerous part and any affected lymph nodes. A colostomy may be performed, where the remaining end of the intestine is opened through the abdomen to allow stool to exit instead of through the anus.
If the cancer has spread to other organs, patients may also receive radiation therapy and chemotherapy.
Colon cancer is a disease with a high chance of cure and can often be completely cured, especially when the cancer is localized to the intestine and has not spread to other parts. Surgery is the primary treatment, and approximately 50% of patients are cured. However, recurrence after surgery remains a significant problem and is often the ultimate cause of death.
How Many Years Can Someone Live with Stage 3 Colon Cancer?
In the United States, the 5-year relative survival rate is 65%. The survival rate for colorectal cancer varies based on several factors, including the stage of the cancer, age, current health, and treatment plan.
If the cancer is detected while it is still localized, the survival rate is 91%. If the cancer has spread to surrounding tissues or organs and/or regional lymph nodes, the 5-year relative survival rate is 72%. If colon cancer has spread to distant parts of the body, the 5-year relative survival rate is 13%.
It is important to remember that statistics on survival rates for individuals with colorectal cancer are only estimates and cannot predict whether cancer will shorten a specific individual’s life. These statistics describe survival trends in groups of people previously diagnosed with the same disease and stage.
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