How Is Colon Cancer Detected?
Colorectal cancer is the second leading cause of cancer deaths in the United States, and it is the fourth most commonly diagnosed. And even though incidences are dropping for people over the age of 65, rates are sadly increasing for people under 50. In 2023 it is estimated that over 150,000 people will be diagnosed with colorectal cancer and over 50,000 will die from it. Since March is National Colorectal Cancer Awareness Month, it’s a good time for a reminder to get screened so that it can be detected as early as possible.
Facts About Colorectal Cancer
Colorectal cancer (CRC) is a term that refers to cancer in either the colon or rectum (though they can also be referred to separately as colon cancer or rectal cancer). As with any type of cancer, colorectal cancer starts as a cluster of mutated cells that starts to grow out of control. Colorectal cancer typically starts in the epithelial cells that make up the inner lining of the large intestine. In the vast majority of cases, the cancer begins as a small growth called a polyp. While often benign at first, polyps can continue to grow and eventually form into a cancerous tumor. Polyps can be categorized into several types, not all of which necessarily lead to cancer:
- Adenomatous: Adenomatous polyps are the most common type and make up about 70% of all polyps. Even though only a small percentage actually become cancerous, they are the most common starting point for malignancy and colorectal cancer.
- Villous/tubulovillous: Villous or tubulovillous adenomas make up only about 15% of polyps detected in colorectal cancer screenings, but they are at a high risk of becoming cancerous. Their structure makes them more difficult to remove than other types of polyp and therefore surgery is sometimes required.
- Serrated: Serrated polyps are so named because of their saw-like appearance. Smaller serrated polyps tend to be benign, but larger versions are more likely to become cancerous and are more difficult to remove.
- Hyperplastic: Hyperplastic polyps are similar to serrated, but they are considered low risk for becoming malignant.
- Inflammatory: Inflammatory polyps are very unlikely to lead to cancer and are more often associated with inflammatory bowel disease. Rather than cellular overgrowth, these polyps develop due to chronic inflammation in the large intestine.
Colorectal cancer, regardless of what type of colon polyp is the starting point, usually takes a long time to develop. A polyp may form and be benign for many years before becoming cancerous and threatening to metastasize. This leaves a lot of time for the overgrowth to be found before it becomes dangerous cancer cells, but it also means that it can continue to develop, undetected, without showing any warning signs until treatment becomes more difficult and more involved.
Colorectal Cancer Signs and Symptoms
The primary purpose of National Colorectal Cancer Awareness Month is to raise awareness about the need for regular cancer screenings. Catching it early in its development is the best-case scenario for treating it in enough time to make a real difference. By the time any warning signs become apparent, it means that the cancer has already formed. Below are some of the most common signs of cancer in the colon or rectum:
- A noticeable change in bowel habits for more than a few days, including: constipation, diarrhea, or a narrowing of stool.
- Tenesmus, the feeling of an incomplete bowel movement even after having one.
- Bright red blood on toilet paper.
- Dark brown or black stool from gastrointestinal bleeding.
- Cramping or other abdominal pain.
- Tiredness, weakness, headaches, or shortness of breath due to anemia.
- Unintended weight loss.
One of the difficult parts of detecting colorectal cancer based on signs and symptoms is that these same symptoms are shared with a number of other gastrointestinal conditions like IBD (which includes ulcerative colitis and Crohn’s disease). So just having these symptoms isn’t necessarily indicative of colon cancer. The only way to know for sure is through cancer screening and other tests.
How Is Colorectal Cancer Detected and Diagnosed?
If symptoms are detected, or if a cancer screening test shows an abnormality, there are a series of steps a doctor will take before making a diagnosis. In addition to verifying that cancer is present, the diagnostic process will also provide valuable information about what stage the cancer is in and therefore what kind of treatment will be necessary. Below are some common steps in the diagnosis of colorectal cancer:
- Physical exam: The first step of any diagnosis is a thorough physical exam and review of the patient’s family history. Since many types of cancer seem to have a genetic component, it’s helpful to know if any other family members have also had cancer.
- Stool test: The presence of blood in the stool is a strong indicator of a problem, but it isn’t always visible to the naked eye. Because of this, the doctor may use a fecal occult blood test (FOBT) or fecal immunochemical test (FIT) to determine whether there is any blood on a microscopic level.
- Blood test: In some cases blood tests may be necessary for the diagnosis, though they also may be used after diagnosis as part of monitoring the disease. Examples of blood tests include complete blood count (CBC), liver enzyme, or tumor marker tests. Tumor marker tests are a common option because they can test for carcinoembryonic antigen (CEA), a very clear indicator of colorectal cancer.
- Colonoscopy: Colonoscopies are also done when screening for colorectal cancer, but they can be employed again to diagnose because it gives the doctor direct visual confirmation of a tumor in the colon or rectum. The test involves the insertion of a long, flexible tube with a camera mounted on the end; it can travel the length of the entire colon and can even remove polyps that are discovered; a less invasive version is the sigmoidoscopy, which only looks at the last part of the colon.
- Biopsy: If, in the course of a colonoscopy, the doctor sees an abnormal growth, a sample can be removed for further testing. In some rare cases, when the growth is larger, part of the colon may have to be removed to perform the proper tests.
- Imaging tests: Imaging tests may also be used in some circumstances, usually in addition to a colonoscopy. X-rays (often combined with a barium enema), CT scans, ultrasound, and MRI are all available depending on the results of other tests and the other circumstances of the patient's condition.
Risk Factors for Colorectal Cancer
Though the specific cause of any type of cancer is still somewhat elusive to doctors, organizations like the American Cancer Society have identified a number of factors that put people at increased risk for colorectal cancer. Some of them, like age and family history of cancer, aren’t able to be mitigated at this point. There are some lifestyle factors, however, that people have control over:
- being overweight or obese
- not getting enough physical activity on a regular basis
- having a diet high in red meat or processed meat
- smoking tobacco
- excessive alcohol use
Colon Cancer Treatment Options
Treatment for colorectal cancer is going to be largely dependent on the stage of cancer when it is first detected and diagnosed. At an early stage, the treatment typically involves removing the problematic polyp or a small area of the inner lining of the colon. As the disease progresses, it gets more difficult for the doctors to be confident that all the cancer cells have been removed. Later stage colorectal cancer typically involves some combination of surgery, radiation therapy, and chemotherapy.
Contact Cary Gastro About Colon Cancer Screening
Colorectal cancer is an intimidating disease, but the fact that it takes such a long time to develop means that there are many chances to catch it early. This is why it’s so important to get screened regularly. The American Cancer Society recommends that people with average risk start getting screened at age 45. If you’re between 45 and 75 and haven’t been screened, please contact us at Cary Gastro to request an appointment.