Colon cancer is one of the most common cancers in the United States. The lifetime risk of developing this type of cancer is 4.4% for men and 4.1% for women. Diagnosing colon cancer early is key to treating it.¹ ²
Since specific symptoms at the early stages of colon cancer are rare, early diagnosis can be problematic. The highly effective way to diagnose this type of cancer is a colonoscopy. Since it's an invasive and expensive procedure, many people avoid it.
Let's take a closer look at the strange symptoms of colon cancer that you can detect on your own.
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When you start having severe symptoms of colon cancer, it's likely to be in its advanced stages. That's why paying close attention to your body and detecting early warning signs is important.
If you spot this type of cancer early, you can have a much wider variety of treatment options and a greater chance of survival.
Local symptoms of colon cancer affect only the colon (the large bowel). They occur in the early stages when the disease hasn't spread to other organs yet. Such symptoms are:
Constipation and/or diarrhea
Blood in the stool (looks bright red or dark red)
Feeling of incomplete emptying of your bowel after using the toilet
All these symptoms could also signal other conditions. However, ignoring them isn't an option. If you see consistent changes in the way you go to the bathroom or experience continuous abdominal pain, it's important to see a doctor.
Many people needlessly worry about seeing their doctor for stool problems because they are afraid of getting a colonoscopy. Conducted under general anesthesia, this procedure isn't painful. Meanwhile, it's highly useful and informative.
Systemic symptoms don't just affect your colon but happen to your entire body. It may be hard to tie these symptoms to colon cancer. However, they are an important warning sign.
Loss of appetite without a reason
Weight loss for unexplained reasons
Nausea and vomiting
Anemia (not enough healthy red blood cells)³
Weakness and fatigue
Similar to local symptoms, the above systemic signs can point to other health conditions. That's why the doctor needs to run appropriate tests to rule out other issues.
Symptoms of colon cancer often mimic signs of other gastrointestinal problems that tend to go away on their own. That's why people often ignore the symptoms and wait for them to subside.
Some strange symptoms of colon cancer that you shouldn't ignore include:
Sharp abdominal pain⁴
Iron deficiency anemia that doesn't go away with treatment⁵
Gradual weight loss
Even if you are sure that these symptoms point to another condition, you should still talk to your doctor about them. They may also schedule some tests to ensure you don't have colon cancer.
While men are at a higher risk of developing colon cancer, gender isn't the only factor contributing to developing this condition. Other risk factors include:
Age — You are more likely to get colon cancer as you age.
Inflammatory bowel disease — People who suffer from IBD for eight years or longer have a higher risk of developing colon cancer.⁶
Family history — If your first-degree relative (parent, sibling, child) has colon cancer, your risk of developing it is higher.⁷
Genetic syndrome — Having a syndrome called familial adenomatous polyposis or Lynch syndrome increases your risk of getting bowel cancer.⁸
Your risks of developing colon cancer can be higher if you are leading an unhealthy lifestyle, which includes the following:
Lack of physical activity
Not enough fiber in your diet
Not enough fruits and veggies in your diet
Alcohol and tobacco use
If you have one of the above risk factors and notice any early signs of colon cancer, it's important to see your doctor as soon as possible.
Several types of colon cancer exist. The most common one is adenocarcinoma. It makes up 95% of colorectal (colon and rectal) cancers. This cancer develops in the lining of the large intestine.⁹
Adenocarcinomas begin their growth as polyps (finger-like growths of tissue). With time, the polyp can turn into cancer. If caught early, it's possible to remove the polyp before it becomes cancerous. Removing it is a routine process that a surgeon performs during a colonoscopy.
Other types of colon cancer are less common. They include:
Gastrointestinal stromal tumors
Peutz-Jeghers syndrome (PJS)
Familial colorectal cancer (FCC)
Juvenile polyposis coli
The rarest type of colon cancer is squamous cell carcinoma (SCC). It represents 0.5% of all colon cancer.¹⁰
If, after reviewing your symptoms and medical history and performing a medical examination, the doctor suspects colon cancer, they can refer you to a gastroenterologist. This specialist may order several tests and procedures:
Colonoscopy — This is the main tool for determining colon cancer and removing polyps in the process. It involves inserting a thin tube with a camera on the tip to check for abnormalities inside the colon.
Biopsy — This procedure involves removing a small piece of tissue from the place where the doctor suspects cancer. Then the lab runs a test to discover or rule out cancer cells.
Image testing — A doctor may order a CT scan to see if cancer has spread or to pinpoint a tumor.
Gene tests — These tests involve gathering the tissue cells during the biopsy and may be tested for specific genes or proteins. This can help determine the best course of treatment.
If a gastroenterologist diagnoses colon cancer, they can set up a personalized course of treatment.
The treatment of colon cancer depends on many factors, including the stage and location that the cancer is in. Common treatment options include:
Ablation or embolization
The doctor will design an individual course of treatment for you. If the issue isn't addressed timely, an individual with colon cancer may experience such complications as:
Developing secondary cancer
To prevent colon cancer, it's important to pay attention to your symptoms, lead a healthy lifestyle, avoid smoking, and exercise regularly.
Timely screening is an important prevention method. Regular screening for people 45 and older is highly recommended by both the American Cancer Society and US Preventive Services Task Force.¹¹ ¹²
Colon cancer can begin without any symptoms. However, some early signs exist. It's important to see a doctor as soon as you have any unusual symptoms or if you are worried about any bowel problems.
If you have any risk factors, it's important to learn all about these strange symptoms and speak to a doctor as soon as you notice them.
At its early stages, colon cancer is highly treatable.
The number one symptom of colon cancer is blood in the stool, followed by changes in bowel habits (constipation and/or diarrhea).
Advanced symptoms of colon cancer are fatigue, abdominal pain, constipation, diarrhea, and long and thin stool. These may also include systemic symptoms where the cancer has spread to other parts of the body.
When colon cancer begins to develop, you may not notice any symptoms. That's why regular screenings are important.
Key statistics for colorectal cancer | American Cancer Society
American cancer society guideline for colorectal cancer screening | American Cancer Society
Colorectal cancer: Screening | U.S. Preventive Services
Colorectal cancer signs and symptoms | American Cancer Society
Types | Standford Medicine
Do I have colorectal cancer? Signs, symptoms and work-up | American Cancer Society
Treating colorectal cancer | American Cancer Society
Colon cancer | Mount Sinai
What are the risk factors for colorectal cancer? | Centers for Disease Control and Prevention