As the name implies, colon cancer begins in the lower part of the large intestine, where food is broken down and nutrients are absorbed. It is more common in older adults and individuals with certain risk factors, but it can affect anyone. In accordance with the size and location of the tumor, colon cancer can cause different symptoms and complications. A colon cancer can be detected by screening tests and diagnosed by biopsy and imaging tests. Surgery, chemotherapy, radiation therapy, targeted therapy, or immunotherapy can be used to treat colon cancer. By avoiding or reducing risk factors, getting regular screening tests, and living a healthy lifestyle, colon cancer can be prevented.
Causes and Risk Factors of Colon Cancer
The exact cause of colon cancer is not known, but it is believed to result from changes in the DNA of the cells in the colon. DNA is the genetic material that contains instructions for how cells grow and function. Cells can grow abnormally and form tumors when DNA is damaged or mutated. Some DNA mutations are inherited from parents, whereas others can be acquired through environmental or lifestyle factors over one’s lifetime.
Colon cancer can be caused by a number of factors, including:
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Most people with colon cancer are over 50 years old. The risk of colon cancer increases with age.
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The risk of colon cancer increases if you have a close relative who has had colon cancer or certain types of polyps (abnormal growths in the colon).
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There are genetic conditions that can increase the risk of colon cancer, such as familial adenomatous polyposis (FAP), Lynch syndrome, Peutz-Jeghers syndrome, and MUTYH-associated polyposis (MAP).
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Having colon cancer, polyps, inflammatory bowel disease (such as ulcerative colitis or Crohn's disease), or radiation therapy to the abdomen or pelvis can increase your risk.
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A diet high in red meat, processed meat, fat, or calories and low in fiber, fruits, and vegetables can lead to colon cancer.
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The risk of colon cancer increases with obesity.
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Colon cancer is associated with physical inactivity.
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The risk of colon cancer can be increased by smoking tobacco.
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Excessive alcohol consumption can increase the risk of colon cancer.
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Type 2 diabetes can increase the risk of colon cancer.
Symptoms of Colon Cancer
It is possible for colon cancer to cause no symptoms in its early stages. However, as the tumor grows or spreads, some symptoms may appear, such as:
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Diarrhea, constipation, or narrowing of the stool are all signs of bowel changes
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Stool blood or rectal bleeding
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Pain, cramps, bloating, or gas in the abdomen
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An incomplete bowel movement or a blockage
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Weight loss that is unexplained
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Weakness or fatigue
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Low red blood cell count (anemia)
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Vomiting or nausea
As colon cancer symptoms vary depending on the size and location of the tumor, some symptoms may also be caused by other conditions that are unrelated to colon cancer. Consult your doctor if your symptoms persist or worsen.
Diagnosis of Colon Cancer
Doctors will ask patients about their medical history, symptoms, and family history in order to diagnose colon cancer. In addition to performing a physical examination, the doctor may order several tests to confirm the diagnosis and determine the stage (extent) of the cancer. Some of these tests include:
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Blood tests
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Stool tests
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Colonoscopy
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Sigmoidoscopy
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Barium enema
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CT scan
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MRI scan
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PET scan
In colon cancer, the stage is determined by the size and depth of the tumor, whether the lymph nodes are involved, and the extent to which it has spread. A colon cancer stage ranges from 0 to 4, with higher numbers indicating more advanced cancer. Cancer stage determines the prognosis (outlook) and treatment options.
Treatment of Colon Cancer
A patient's treatment options for colon cancer depend on the stage, location, and type of cancer, as well as their overall health and preferences.
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The most common treatment for colon cancer is surgery. The type of surgery depends on the size and location of the tumor. It involves removing both the tumor and the surrounding healthy tissue (margin) to ensure that no cancer cells remain. Some common types of surgery include:
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Polypectomy
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Local excision
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Colectomy
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Lymph node removal
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Metastasectomy
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A chemotherapy treatment uses drugs to kill or prevent the growth of cancer cells. For patients with advanced or metastatic colon cancer, chemotherapy can be used as a palliative treatment to relieve symptoms and improve quality of life, before surgery (neoadjuvant), after surgery (adjuvant), to kill any remaining cancer cells and reduce the risk of recurrence, or as a palliative treatment to kill any remaining cancer cells and reduce the risk of recurrence. There can be side effects to chemotherapy, such as nausea, vomiting, hair loss, fatigue, infection, or nerve damage. Chemotherapy can be administered by mouth (oral), by injection into a vein (intravenous), or by infusion into the abdomen (intraperitoneal).
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Cancer cells are destroyed or stopped from growing by radiation therapy, which uses high-energy rays and particles. For patients with advanced or metastatic colon cancer, radiation therapy can be given before surgery (neoadjuvant) to shrink the tumor and make it easier to remove, after surgery (adjuvant) to kill any cancer cells remaining and reduce the risk of recurrence, or as a palliative treatment to alleviate symptoms and improve quality of life. In external beam radiation therapy, rays are directed at the tumor site by a machine, while in internal radiation therapy (brachytherapy), radioactive sources are placed inside or near the tumor. Infertility, skin irritation, diarrhea, bladder problems, and sexual dysfunction can all result from radiation therapy.
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During targeted therapy, drugs are used that target specific molecules or pathways involved in the growth and survival of cancer cells. In patients with advanced or metastatic colon cancer with certain genetic mutations or characteristics, targeted therapy can be used alone or in combination with chemotherapy or radiation therapy. Skin rash, diarrhea, high blood pressure, bleeding, and wound healing problems can occur as a result of targeted therapy.
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A type of treatment called immunotherapy involves using drugs to stimulate or enhance the immune system's ability to fight cancer cells. For patients with advanced or metastatic colon cancer with certain genetic mutations or characteristics, immunotherapy can be used alone or in combination with chemotherapy or targeted therapy. Aside from fatigue, fever, chills, rash, itching, nausea, diarrhea, colitis, liver problems, thyroid problems, or lung problems, immunotherapy can cause side effects.
Depending on the patient's response and tolerance to treatment, the treatment plan may be modified over time. The doctor will discuss with the patient the benefits and risks of each treatment option.
Prevention of Colon Cancer
While some cases of colon cancer may not be preventable, especially if they are genetic or inherited, there are some ways to decrease the risk or detect colon cancer early, such as:
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Having regular screening tests
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Eating a healthy diet
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Maintaining a healthy weight
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Being physically active
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Avoiding smoking and alcohol
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Consulting a doctor
In addition to colon cancer, these symptoms can also be caused by other conditions. However, it is better to be safe than sorry and seek medical attention as soon as possible. Early detection and treatment increase the chances of survival and recovery.
