Colon cancer starts when abnormal growths, called tumors, appear in the large intestine. In the early stages, it often doesn’t cause any symptoms. However, it’s important to visit a healthcare provider if you notice constant changes in your bowel habits.
The large intestine, also known as the colon, is responsible for removing salt and water from waste of solid. After this process, the waste moves over the rectum then leaves the body by way of the anus. Rectal cancer begins in the rectum, which is the last part of the large intestine, closest to the anus.
When colon and rectal cancer occur together, it is known as colorectal cancer. This type of cancer is quite common.
As stated by the American Cancer Society, colorectal cancer is the 3rd most commonly diagnosed cancer in the United States, following skin cancers.
Doctors advise regular colorectal cancer checking for adults aged 45 to 75 to help with early detection and prevention.
Symptoms
Symptoms and signs of colon cancer may vary, and they may include a range of issues related to bowel movements and general health. Common symptoms are constipation or diarrhea, modifications in stool consistency like loose or narrow stools, and bloody stool. The presence of blood can cause stools to appear dark brown or black, or result in bright red bleeding from the rectum. Abdominal pain and bloating are also possible symptoms. Some individuals may experience continual urges to defecate even after having bowel movements. Additionally, colon cancer may lead to weakness and extreme tiredness, unintentional weight loss, iron deficiency, and irritable bowel syndrome. It’s important to note that abdominal pain and weight loss usually become more prominent in the later stages of the disease.
If colon cancer extends to other areas of the body, like the liver, it may lead to additional symptoms like jaundice.
In the early stages of colon cancer, symptoms are often not present. However, as the disease progresses, symptoms may start to become more noticeable. Early signs can include bloody stool, changes in bowel movements like constipation, diarrhea, or stools that are narrow and ribbon-like. A sensation of not completely emptying the bowels after a bowel movement, abdominal pain, or bloating can also occur. Other early symptoms may include nausea and vomiting, anemia from intestinal bleeding, loss of appetite, extreme tiredness, weakness, and unintentional weight loss.
Causes
Normally, cells in the body follow a controlled process of growing, dividing, and eventually dying. Cancer can occur when this process goes wrong, and cells start growing and dividing uncontrollably without dying when they should.
Scientists are still not completely sure what causes colon cancer, but particular factors can increase the chance of developing it. Cancer begins due to changes in the DNA of cells. DNA contains genes that control how cells divide and grow. Two important types of genes are involved: one is oncogenes and another is tumor suppressor genes. Oncogenes help cells stay alive and divide, while tumor suppressor genes help regulate cell division and death. When the DNA changes, these genes can become faulty, leading to uncontrolled cell growth and possibly resulting in cancer of the colon.
Polyps are small growths that can appear on the internal side of the colon. While most polyps are not cancerous, some types can eventually lead to cancer. One type, known as an adenomatous polyp, increases the chance of developing colon cancer. These polyps grow on the inner lining of the large intestine.
If colon cancer develops, cancerous cells can extend to other areas of the body. This spread happens through the lymph and blood systems and is known as metastasis. Once cancer spreads, it can invade and damage healthy tissues, making the condition more serious and harder to treat.
Risk Factors
Several factors can increase the risk of developing colon cancer. One significant risk factor is having a family history of the disease. If a mother or father, sibling, or child has had rectal or colon cancer, it can raise your risk. Additionally, having a personal history of ovarian, rectal, or colon cancer may also increase your risk. If you have had polyps that are 1 cm or larger, or polyps with abnormal cells, you are at a higher risk as well.
Genetic conditions that run in families, like Lynch syndrome, can also increase the likelihood of developing colon cancer. Chronic conditions like Crohn’s disease or ulcerative colitis, especially if they have lasted for 8 years or more, are another risk factor.
Lifestyle choices can also play a role in increasing cancer risk. Regularly consuming alcohol three or more times a day and smoking cigarettes can both contribute to a higher risk of colon cancer. Additionally, being older, lack of physical activity, and following a high-fat, low-fiber diet that is low in fruits and vegetables are associated with an increased risk.
Ethnicity and race may also affect the timing of a colon cancer diagnosis. For instance, Asians, African Americans, and people of Hispanic descent may be diagnosed at a further stage of the disease.
Treatment Options
The treatment for colon cancer varies based on the kind and stage of the disease, as well as the patient’s age, health, and other individual factors. There is no single intervention approach, so healthcare providers may use a combination of surgery, radiation therapy, and chemotherapy, to manage the cancer, stop its spread, and alleviate symptoms.
Surgery
Surgery is often the primary treatment for the starting stage of colon cancer. If the cancer is detected in a polyp, a procedure called a polypectomy may be sufficient to remove the cancerous growth. For more advanced cases, a colectomy may be required. This surgery involves removing some part of the colon that contains cancer, along with some surrounding tissue. In some cases, surrounding lymph nodes may also be removed to decrease the chance of cancer spreading. After the removal, the healthy portion of the colon may be reattached, or a stoma may be created.
Chemotherapy
Chemotherapy involves using medications to disrupt the process of cell division, targeting rapidly dividing cancer cells. These drugs interfere with the proteins or DNA in cancer cells, causing damage and death. Although chemotherapy also affects healthy, rapidly dividing cells, these are typically able to recover from the treatment, unlike cancer cells. Chemotherapy is usually administered in cycles, allowing the body time to recover between treatments.
An oncologist may suggest chemotherapy to:
- Shrink a tumor before surgery, making it easier to eliminate
- Destroy any remaining cancer cells after surgery
- Treat cancer that has spread to other organs
Radiation Therapy
Radiation therapy works by targeting cancer cells with high-energy rays, like gamma rays or X-rays. This can be done through external radiation, where rays are directed from a machine external side of the body, or internal radiation, where radioactive materials are placed near the cancer site.
Diagnosis
To diagnose colon cancer, a physician will first perform a thorough physical examination and review the patient’s personal and medical histories of the family. Several diagnostic techniques may be used to detect and stage the cancer.
A colonoscopy involves inserting a long, flexible tube alongside a camera into the rectum to observe the colon internally. Preparation for this procedure typically includes a special diet and bowel cleansing with laxatives. If polyps are found, they are removed and sent for biopsy to check for precancerous or cancerous cells. A flexible sigmoidoscopy, which examines only part of the colon, may be used if a full colonoscopy is not needed.
Another diagnostic method is the double-contrast barium enema, where a liquid barium is injected into the colon, followed by air to provide clearer X-ray images of the colon and rectum. Tumors and polyps will appear as dark outlines on these images.
If colon cancer is confirmed by biopsy, further imaging tests like chest ultrasounds, X-rays, or CT scans may be ordered to check for cancer spread to the liver, lungs, or abdomen. The stage of the cancer, determined by the size of the tumor and its extent to lymph nodes and far organs, will guide the treatment options and prognosis.
Prevention
While there is no confirmed way to prevent colon cancer, several lifestyle changes can help reduce the risk. Maintaining an average weight and engaging in regular physical exercise is important for overall health and may lower the risk of colon cancer. A diet rich in whole grains, fruits, and vegetables can also be beneficial, while decreasing the intake of red meat and saturated fats may further decrease the risk.
Additionally, it’s wise to consider reducing alcohol consumption and quitting smoking, as these habits can contribute to the development of colon cancer. Adopting these preventive measures can contribute to better health and potentially lower the risk of colon cancer.
Summary
Colon cancer develops when cells in the large intestine grow uncontrollably. Risk factors include family history, personal history of certain cancers or polyps, genetic conditions like Lynch syndrome, chronic inflammatory diseases, and lifestyle factors such as excessive alcohol consumption and smoking.
Diagnosis involves physical exams, colonoscopy, and imaging techniques like double-contrast barium enema. Treatment options depend on the cancer’s stage and may include surgery, chemotherapy, and radiation therapy. Preventive measures include maintaining a healthy weight, exercising regularly, eating a balanced diet, and avoiding excessive alcohol and smoking.
