Colorectal cancer is the cancer of the colon and rectum. In this type of cancer a malignant tumor arises from the inner wall of the large intestine.
The colon is lined by colorectal cells. Basically colorectal cancer is the uncontrolled growth of these cells. And these cells are malignant.
They grow without respect to any borders and through the colon and into the neighboring structures into the abdominal cavity. They can also break off and go to other parts of the body, known as metastasis.
Cancer that begins in the colon is called colon cancer, and cancer that begins in the rectum is called rectal cancer. Cancers affecting either of these organs also may be called colorectal cancer.
Colorectal cancer occurs when some of the cells that line the colon or the rectum become abnormal and grow out of control. The abnormal growing cells create a tumor, which is the cancer. Risk factors include heredity, colon polyps, and long standing ulcerative colitis. Most colorectal cancers develop from polyps. Removal of colon polyps can prevent colorectal cancer.
Since colon polyps and early cancer can have no symptoms, regular screening is important. Diagnosis can be made by barium enema or by colonoscopy with biopsy confirmation of cancer tissue.
Surgery is the most common treatment for colorectal cancer.
Colorectal Cancer Causes
There are many causes for colorectal cancer. The causes of colorectal cancer include:
- Polyp formation
- Genetic defects on chromosomes 2, 5, 17, and 18
- Family history of colon cancer related to genetic syndromes, such as HNPCC (Hereditary nonpolyposis colorectal cancer) syndrome of familial adenomatous polyposis (FAP).
- Eating a high-fat, low-fiber/calcium diet
- Lack of exercise
Colorectal cancer is rare in young people. Fewer than 6 percent of cases occur before the age of 50 years old. Incidences increase markedly after the age of 50, continues to rise until the age of 75, and then tapers off. The average age at the time of diagnosis is 60 years old.
The main associated risk is a high fat, low fiber diet. There are also other individuals who are at risk for colon cancer, including those with a family history of colon cancer. Other risk factors include age and that is because your risk of colon cancer increases as your age increases. There’s people with a history of polyps also are at risk. Finally people with a history of inflammatory bowel disease also known as ulcerative colitis are also at risk.
The other large categories of individuals that are also at significant risk are those that can inherit a genetic defect which puts them at high risk to develop colon cancer in their lifetime. These are known as FAT and HNPCC which are short forms that stand for two types of hereditary genetic diseases.
Colorectal Cancer Symptoms or Sign of Colorectal Cancer
Unfortunately, colorectal cancer symptoms or sign of Colorectal Cancer may not be evident in an early stage. For this reason, it is very important to have regular examinations, called colorectal screenings, to detect early problems.
However, not all colorectal cancers are without symptoms. One of the early symptoms of colon cancer may be bleeding. Often, tumors bleed only small amounts, off and on, and evidence of the blood is found only during chemical testing of the stool. When tumors have grown larger, other colorectal cancer symptoms may develop. They include:
- Change in bowel habits and bowel incontinence
- Constipation, diarrhea
- Blood on or in the stool
- Unexplained anemia, shortage of red blood cells
- Unusual stomach or gas pain
- Unexplained unintentional weight loss with unknown reason
- Weakness or tiredness
- Narrow stools
- General stomach discomfort (bloating, fullness, and/or cramps)
- Frequent gas pains
Colorectal Cancer Treatment
The most common form of colorectal cancer treatment is surgery to remove the cancer.
Dependent on the stage of the colorectal cancer at the time the patient presents with the disease, addition of chemotherapy or radiation therapy may also be rendered.
Another way of treating colorectal cancer especially in more advanced stages is to use chemotherapy.
Chemotherapy is used sometimes immediately after surgery to help prevent cancers from coming back later on in a patient’s lifetime. This type of chemotherapy treatment is called adjuvant chemotherapy treatment. This type of treatment is given because the cancer has a high likelihood of coming back again in other places even after successful removal of the primary tumor.
When the tumor has extended right through the bowel wall and has come to involve lymph nodes then in those situations, the patients have a very high likelihood of cancer coming back and a treatment with chemotherapy is given to reduce the risk.
Finally the other situation chemotherapy is where the disease comes back elsewhere, liver or lung. When it has escaped or metastasized to too many places, then using intravenous treatment is the treatment of choice. There are situations where surgery may also be used again.
In specific instances in which the disease has recurred in another organ such as the liver or the lungs, surgery can sometimes still be offered to these patients to remove those recurrent tumors in those organs and provide for a longer survival and sometimes even the cure of these patients.
In regard to radiation therapy, this is frequently used in colorectal cancer, where following surgery or sometimes before surgery, the radiation is given to the rectal area. There are other modalities for treatment of colorectal cancer which at this point are considered more experimental rather than the standard of care.
One such therapy involves the realm of immunotherapy where, in this therapy, the physician aims to strengthen or to boost the patient’s immune system for destruction of the tumor. This form of therapy is considered more of a trial or experimental therapy.
Colorectal Cancer Prognosis and Survival rate
The colorectal cancer prognosis and survival rate depend on the stage of the disease. Surgery is the main treatment for colorectal cancer, is curative in about 70% of cases.
If the patient’s colorectal cancer does not come back (recur) within 5 years, it is considered cured. This is because colorectal cancer rarely comes back after 5 years. Stage I, II, and III cancers are considered potentially curable. In most cases, stage IV cancer is not curable.
Stage I has a 90% 5-year survival. Stage II has a 75-85% 5-year survival, and Stage III a 40-60% 5-year survival. These numbers take into account that for stage III patients (and in some studies, stage II patients) chemotherapy improves the chance of 5-year survival.
Patients with stage IV disease rarely live beyond five years and the median survival (meaning half the patients live longer and half shorter) with treatment is between 1 and 2 years.