18 اسفند Everything about Colorectal cancer
Dr. Alemrajabi – Colorectal cancer starts in the colon or the rectum. These cancers can also be called colon cancer or rectal cancer, depending on where they start. Colon cancer and rectal cancer are often grouped together because they have many features in common.
It is the second leading cause of cancer death in women, and the third for men. However, due to advances in screening techniques and improvements in treatments, the death rate from colorectal cancer has been falling.
Colorectal cancer may be benign, or non-cancerous, or malignant. A malignant cancer can spread to other parts of the body and damage them.
In general, colon cancer begins when healthy cells in the colon develop changes (mutations) in their DNA. A cell’s DNA contains a set of instructions that tell a cell what to do.
Healthy cells grow and divide in an orderly way to keep your body functioning normally. But when a cell’s DNA is damaged and becomes cancerous, cells continue to divide — even when new cells aren’t needed. As the cells accumulate, they form a tumor.
With time, the cancer cells can grow to invade and destroy normal tissue nearby. And cancerous cells can travel to other parts of the body to form deposits there (metastasis).
Most colon cancers develop within polyps (adenoma). These are often found inside the bowel wall. But It usually begins as small, noncancerous (benign) clumps of cells called polyps that form on the inside of the colon. Over time some of these polyps can become colon cancers. Polyps may be small and produce few, if any, symptoms. For this reason, doctors recommend regular screening tests to help prevent colon cancer by identifying and removing polyps before they turn into cancer.
If colon cancer develops, many treatments are available to help control it, including surgery, radiation therapy and drug treatments, such as chemotherapy, targeted therapy and immunotherapy.
But in general, the following conditions can increase the likelihood of a polyp becoming malignant.
- Size larger than 1 cm
- More than 2 polyps
- Observation of dysplasia in polyps when they are removed
Symptoms of colorectal cancer
Like stomach cancer, the disease may not show any particular symptoms in the early stages, so keep in mind that screening tests are very important, especially at older ages. But in general, the following items can be symptoms of this disease. So if you see these symptoms and there is no specific reason for their occurrence, it is better to see a doctor for a better evaluation.
- A persistent change in your bowel habits, including diarrhea or constipation or a change in the consistency of your stool
- Decreased stool diameter in the event that defecation occurs after one day and there is no other reason for it.
- Weakness or fatigue
- Unexplained weight loss
- Persistent abdominal discomfort, such as cramps, gas or pain
But what puts you at risk for colon cancer?
- A personal history of colorectal cancer or polyps. If you’ve already had colon cancer or noncancerous colon polyps, you have a greater risk of colon cancer in the future.
- Older age. Colon cancer can be diagnosed at any age, but a majority of people with colon cancer are older than 50. The rates of colon cancer in people younger than 50 have been increasing, but doctors aren’t sure why.
- Family history of colon cancer. You’re more likely to develop colon cancer if you have a blood relative who has had the disease. If more than one family member has colon cancer or rectal cancer, your risk is even greater.
- Smoking and drinking alcohol . People who smoke or drink heavily may have an increased risk of colon cancer.
- Physical inactivity and obesity. People who lead an inactive lifestyle, meaning no regular exercise and a lot of sitting, and people who are overweight or obese may have an increased risk of colorectal cancer.
- Radiation therapy for cancer. Radiation therapy directed at the abdomen to treat previous cancers increases the risk of colon cancer.
- Low-fiber, high-fat diet. Colon cancer and rectal cancer may be associated with a typical Western diet, which is low in fiber and high in fat and calories. Research in this area has had mixed results. Some studies have found an increased risk of colon cancer in people who eat diets high in red meat and processed meat.
- Inflammatory intestinal conditions. Chronic inflammatory diseases of the colon, such as ulcerative colitis and Crohn’s disease, can increase your risk of colon cancer.
Because of complexities of gastrointestinal cancers, such as colon cancer, it is best to always think of a solution before an accident occurs. Here are some ways to prevent colon cancer:
Colorectal Cancer Screening Tests
- The fecal immunochemical test (FIT) uses antibodies to detect blood in the stool. It is also done once a year in the same way as a gFOBT.
- The stool DNA test combines the FIT with a test that detects altered DNA in the stool. For this test, you collect an entire bowel movement and send it to a lab, where it is checked for cancer cells. It is done once every three years.
- Colonoscopy is similar to flexible sigmoidoscopy, except the doctor uses a longer, thin, flexible, lighted tube to check for polyps or cancer inside the rectum and the entire colon. During the test, the doctor can find and remove most polyps and some cancers. Colonoscopy also is used as a follow-up test if anything unusual is found during one of the other screening tests.
- Computed tomography (CT) colonography, also called a virtual colonoscopy, uses X-rays and computers to produce images of the entire colon, which are displayed on a computer screen for the doctor to analyze.
You can take steps to reduce your risk of colon cancer by making changes in your everyday life. Eat a variety of fruits, vegetables and whole grains, stop smoking, Exercise most days of the week, Maintain a healthy weight, don’t drink alcohol or drink in moderation.
What are the treatments if you are diagnosed with colon cancer?
Surgery for early-stage colon cancer
If your colon cancer is very small, your doctor may recommend a minimally invasive approach to surgery, such as:
- Removing polyps during a colonoscopy (polypectomy). If your cancer is small, localized, completely contained within a polyp and in a very early stage, your doctor may be able to remove it completely during a colonoscopy.
- Endoscopic mucosal resection. Larger polyps might be removed during colonoscopy using special tools to remove the polyp and a small amount of the inner lining of the colon in a procedure called an endoscopic mucosal resection.
- Minimally invasive surgery (laparoscopic surgery). Polyps that can’t be removed during a colonoscopy may be removed using laparoscopic surgery. In this procedure, your surgeon performs the operation through several small incisions in your abdominal wall, inserting instruments with attached cameras that display your colon on a video monitor. The surgeon may also take samples from lymph nodes in the area where the cancer is located.
Chemotherapy uses drugs to destroy cancer cells. Chemotherapy for colon cancer is usually given after surgery if the cancer is larger or has spread to the lymph nodes. In this way, chemotherapy may kill any cancer cells that remain in the body and help reduce the risk of cancer recurrence.
Chemotherapy might also be used before an operation to shrink a large cancer so that it’s easier to remove with surgery.
Chemotherapy can also be used to relieve symptoms of colon cancer that can’t be removed with surgery or that has spread to other areas of the body. Sometimes it’s combined with radiation therapy.
For some people with low-risk stage III colon cancer, a shorter course of chemotherapy after surgery may be possible. This approach may reduce the side effects compared with the traditional course of chemotherapy, and may be just as effective.