Uncontrolled growth of cells in rectum or colon (large intestine) is known as colorectal cancer. This is also called bowel cancer or colon cancer. It can also originate in the appendix. This kind of cancer usually initiates in the form of tiny polyps, which is also known as adenomatous polyps. Majority of the colon polyps remain benign in nature, but a few of them can turn cancerous. Polyps are so small that they generally do not show any symptom of being cancerous or rather show only a few symptoms. This is the reason why it is recommended to go for routine screening for early detection of colorectal cancer.
The major causes of colorectal cancer have been observed to be increasing age and lifestyle. Only a few of the colorectal cancer cases are related to primary genetic disorders. This type of cancer normally begins in the bowel’s lining and if such cancers do not get proper treatment in time, then it can extend to the muscle layer beneath and also stretches through bowel wall. Screening of colorectal cancer is recommended once someone attends the age of fifty and it should be done regularly until the age of 75.
Symptoms of colorectal cancer vary with the place from where the tumor originates in the bowel. Other factors, which affect the symptoms of colorectal cancer, include its spread to other areas of the body. In a number of cases of colorectal cancer, there are no symptoms in the initial stages. Symptoms also do not occur in treatable stages of colorectal cancer. Symptoms start to come up when the cancer begins to grow in size. Some of the common symptoms of colorectal cancer, which one should keep an eye on include:
- Worsening of constipation
- Change in frequency of regular bowel movement
- Blood in the stool, which might appear very dark or bright red
- Diarrhea or constipation is also a sign of colorectal cancer, but these are normally persistent in succases of cancer
- Narrower stool than usual. Long and thin stools are also called pencil stools.
- Decrease in caliber of the stool
- Most of the times there can be a feeling that the bowel is not entirely empty
- Rectal bleeding as well as cramping is another common symptom
- Bloating with abdominal discomfort, which includes fullness, more than normal gas pains, cramps etc.
- Vomiting or nausea, especially in those, who have crossed the age of fifty
- Consistent fatigue
- Weight loss without any significant reason
- Anemia and rectal bleeding can be riskier features in those, who are over fifty years of age
For those who have attended the age of fifty, there are a number of tools or diagnostic tests for detecting colorectal cancer at an early stage. These tests can help in recognizing pre-cancerous conditions. These tests include:
- FOBT (Fetal occult blood test): This is used for checking blood that is hidden in the stool.
- Colonoscopy: This test checks the entire colon and the rectum with the help of a colonoscope. This is one of the well-known examinations of colorectal cancer.
- Sigmoidoscopy: This examines the lower colon and the rectum with the aid of lighted equipment known as the sigmoidoscope.
- Virtual colonoscopy: This is almost similar to a standard colonoscopy. However, an external machine is used for scanning in place of a device, which is placed inside the colon. In this method, there is no need of inflating the colon with gas to get proper scanning results.
- DRE (digital rectal exam): This is another screening test for colorectal cancer, where the physician insert a gloved and lubricated finger inside the rectum for feeling any kind of abnormal area.
- Genetic Testing: Normally physicians no rely on genetic testing for diagnosing colorectal cancer at an early stage, but in some cases this can be appropriate. This might be used for determining the risk of developing genetic forms of cancer.
Other tests done to diagnose and confirm the presence of colorectal cancer include:
- X-rays and dyes: A doctor might use barium enema for evaluating the whole of the colon with the help of an x-ray. The bariums coats and fills the bowel lining and create clear outlines of the rectum and the colon.
- CT scan: CT scans can be combined with virtual colonoscopy for getting detailed images of the colon from within. CT scan of the pelvis, abdomen, and chest is done to determine the extent of the cancer. Virtual colonoscopy is recommended when standard colonoscopy is not possible.
- Biopsy: Tumor biopsy is normally done while sigmoidoscopy or colonoscopy is done and this diagnostic test also depend on the cancer’s location.
Palliation or Curation can be two main aims of treatment for colorectal cancer. The choice of treatment depends on a number of factors. These include the preferences and health of the patient along with stage of the tumor. If colorectal cancer is detected at an early stage, then treatment can be curative. For cancers that have progressed beyond a level the main aim of treatment is palliation. The primary options for treatment include:
- Surgery: For localized and small cancer that is at an advanced stage, colonoscopy can be used for removing the polyp completely. A few of the larger polyps are removed with the help of laparoscopic surgery. In such a surgery, surgeons make multiple incisions in the abdominal wall. Then they insert instruments that have cameras attached to them to take pictures of the colon. Samples from the lymph nodes are also taken from the location of the cancer. For cancers that have extended through the colon, partial colectomy is surgery is used for removing the part of the colon together with some of the normal tissues surrounding the cancer. For very advanced colorectal cancers, physicians might go for an operation for relieving any blockage in the colon. Chemotherapy might be used prior to this type of surgery. This kind of surgery is primarily done to improve signs of cancer and not to cure it.
- Chemotherapy: In this procedure drugs are used for killing the cancer cells, to relive several symptoms, and also to control the growth of the tumor. When colorectal cancer extends beyond the colon wall and make its way to lymph nodes, then doctors can also recommend chemotherapy.
- Targeted Drug Therapy: In this method drugs are administered for targeting particular defects, which enable the cancerous cells to propagate. This option is primarily available for patients suffering from advanced colon cancer.Drugs mainly used in this procedure include cetuximab, bevacizumab, panitumumab, etc.
- Radiation Therapy: Powerful sources of energy are used in radiation therapy. This includes x-rays for killing cancer cells or to decrease the size of the tumor before going for a surgery. If the size of the tumor is reduced, then removing it with a surgery becomes easier as well. This also helps in relieving many symptoms of rectal and colon cancer. This therapy is hardly used in treatment of colorectal cancers at an early stage. However, when rectal cancer penetrates through the colon wall, then this procedure is used. Radiation therapy is also used together with chemotherapy and is also used following a surgery for minimizing the risk of the cancer spreading to other areas of rectum.
Close observation, proper medication, and better lifestyles are some of the ways that can help in preventing colorectal cancer. The main changes that can help in prevention of colorectal cancer include:
- Screening: Majority of the colorectal cancers start from adenomatous polyps, which makes it acquiescent to screening. If colorectal cancer is screened properly, then it can help in bringing down the mortality rate by almost sixty percent.
- Lifestyle: Presently doctors recommend increased consumption of fruits, vegetables, and whole grains to avoid the occurrence of colorectal cancer. Decrease in red meat intake is also recommended by experts. However, there is not enough evidence in support of consumption of fruits, vegetables, or fiber.
- Medication: Celecoxib and Aspirin are said to be helpful in reducing the risk of developing colorectal cancer. This is mainly for those, who are at a greater risk of colorectal cancer. Intake of vitamin D along with blood levels are related to lesser risk of developing colon cancer.