WHAT IS IT?
colorectal cancer is the uncontrolled growth of abnormal cells in that part of the intestine. These cells can invade and destroy tissue that is around him. If they enter the bloodstream or lymph, can be extended anywhere in the body and cause damage to other organs. In this expansion process is called metastasis.
The colon and rectum are part of the digestive system. The colon is the first section of intestine. It will continue to absorb nutrients and water from foods have been eaten, as in the small intestine, and serves as a container for waste material. This material is advancing to the rectum, the last part of the large intestine until it is expelled outside through the anus.
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The colon is divided into four segments: ascending, transverse, descending and sigmoid. The rectum joins the sigmoid colon.
Both the colon and rectum are made up of several layers of tissue. As they affected one or another layer, and the prognosis of cancer.
Cancer that begins in the colon is called colon cancer that begins in the rectum, cancer of the rectum. According
is affected one side or another, the symptoms will be different and diagnostic tests will be different and more effective in detecting cancer according to the area displayed.
is thought that colon cancer progresses slowly before being diagnosed as such. Before the development of a cancer often injuries occur in the gut that are called dysplasia or adenomatous polyps.
Some types of polyps are not cancerous, but the fact of having increased the likelihood of having, in the future, cancer in the area of \u200b\u200bthe intestine.
The colon cancer is the second leading cause of cancer death after lung cancer in men and breast cancer in women. Between 22% and 36% of cases presented advanced disease and in these cases, the survival rate round to zero.
In our country there are 11,000 new cases per year. Mortality caused by this cancer is 10 deaths per 100,000 inhabitants per year, with rising trend.
colon cancer has become more common in developed countries. Together represent 15% of the tumors diagnosed in men.
survival rate five years is 90% in those who have had early detection of cancer. But detected only 37% of these cancers at an early stage.
If the cancer has spread to nearby organs or lymph nodes, the survival rate decreases to 65%. And if it has spread to distant organs, the five-year rate is 8%.
RISK FACTORS
The exact causes of colorectal cancer are not known, although many studies have shown that a number of factors that increase the risk for this disease:
Age: This type of cancer is more common among those of around fifty years or older. Although this does not mean it can not occur in young people.
genetic predisposition, personal or family history of polyps or colon cancer. Polyps are benign growths on the inner walls of the colon and rectum. There is a condition called familial polyposis, which is training hundreds of polyps in the colon and rectum. If left untreated, can lead to cancer. About 10% of cases of colorectal cancer are due to inherited genetic mutations.
Inflammatory bowel disease prior : patients with ulcerative colitis with an evolution of 7-10 years are at increased risk of colo-rectal cancer. Also patients with Crohn's disease have a 20 times higher risk of generating a colo-rectal cancer.
personal history of other cancers : in women who have had uterine cancer, ovarian or breast cancer, are increased chances of getting colon cancer.
Habit sedentary lifestyle: a sedentary lifestyle has been shown in numerous studies that favors the development of cancer.
Diets low in fiber, fruits and vegetables and too much fat harmful. Carotenoids, substances found mainly in fruits and vegetables have many beneficial functions such as the fight against the formation of these tumors and immune system booster.
snuff consumption: people who smoke 20 cigarettes a day were twice as likely to develop colon cancer.
Can we prevent this cancer?
By not really know the cause specific to this cancer can not be prevented although you can respond effectively to early diagnosis.
polyps can be detected in its early stages and remove them to avoid the possible formation of cancer cells.
People can reduce or change those risk factors that may change as the following:
- Maintain a moderate daily activity helps lower cancer risk.
- Eating a diet low in fat, high in vegetables and fruits prevents the formation and growth of this cancer.
- Stop smoking. The snuff affects the formation of many types of cancer. In the colon, male smokers are 34% more likely to suffer, and women smokers 43%.
-Drink alcohol in moderation.
As for genetic factors predisposing , what can people who have them is to go often to revisions. Your doctor will be able to give all the information they need and possible means of diagnosis to choose from.
There have been several epidemiological studies which have shown that people who regularly take aspirin and other nonsteroidal antiinflammatory drugs (NSAIDs) have a risk between 40% and 50% lower colorectal cancer and polyps adenomas. These studies have not fully demonstrated the relationship of these drugs in cancer, nor has determined the minimum effective dose, the mechanism of action or populations that provide the greatest benefit.
Other epidemiological studies indicate that there is an association between estrogen replacement therapy for women who are past menopause, with a reduced risk of developing colo-rectal cancer. Nor have evaluated whether this effect outweighs the risk caused by this therapy to increase the chances of uterine and breast cancer.
both anti-inflammatory drugs such as calcium, are being studied to assess their relationship to cancer.
stage of the cancer types
colorectal cancer
Approximately 90% of colorectal cancers are adenocarcinomas. These are tumors that occur in the glandular cells lining the colon and rectum.
Other tumors that may occur, though much less commonly, carcinoid tumors and gastrointestinal stromal. The first develop from hormone-producing cells of the intestine and second, in the connective tissue and muscle layers of the wall of the colon and rectum.
adenocarcinomas may present different forms, the vegetative stand, with growth into the light, infiltrating forms, that by occupying the wall to produce infiltrating strictures and retraction, and ulcerative forms. Spread
This cancer can spread through the lymphatic route, the bloodstream and implementation.
The local spread is mainly of circular form around the bowel wall infiltrated all layers, producing a narrowing of the lumen of the intestine. Once all layers are affected, the invasion of the lymphatic and venous pathway. If that spread
is performed longitudinal, rather than circular shape, the extension occurs more slowly, being more limited cancer at baseline.
In 80% of patients, perineural infiltration occurs in the nerves of the area, causing pain.
The tumor can spread locally, invading neighboring structures or adjacent organs.
metastases occur because the cancer cells enter the blood or lymph, and they distribute them to other areas of the body. Usually if distributed through the blood, often frequent metastases in liver, lung and spine. If it happens through the lymph lymphatic metastasis will probably bladder or prostate.
Staging Classification
There are several classification systems colorectal cancer, who are the Dukes system, Astler-Coller and AJCC / TNM. The latter stages designated with Roman numerals 0 through IV. Dukes system uses letters from A to C. And Astler system from A to D. 
These stages describe the extent of cancer in relation to the wall of the colon or rectum, organs attached to them and distant organs.
system AJCC / TNM describes the extent of primary tumor (T), absence or presence of metastases in lymph nodes near (N) and the absence or presence of distant metastases (M).
Interactive Graphic
Stages T
describe the involvement of different layers that make up the wall of the rectum and colon. These layers are:
- mucosa or lining.
- Muscularis mucosa: a thin layer of muscle tissue beneath the mucosa.
- Submucosa: connective tissue beneath the thin muscle layer.
- Muscularis itself: thick layer of muscle that contracts to move the bowel contents.
- subserosa: thin layer of connective tissue.
- Serous: thin layer covering the outer surface of some parts of the intestine.
T x : You can not know the extent of tumor because it is not fully formed.
T is : the cancer is in its beginning and has not spread beyond the innermost layer, the mucosa of the colon or rectum. IT
: The cancer has gone through the mucosa and the next layer, the muscularis mucosa and extends into the submucosa. T II
: layers of the mucosa, muscularis mucosa and submucosa are affected and the cancer spreading to the muscularis propria.
T III: the muscularis propria completely affected and begins to become pregnant the subserosa. T
IV: The cancer has invaded the organs or tissues. Stages
N N x : not known if the lymph nodes are involved or not because you do not have enough data.
N 0 : no affected lymph node.
N 1: the number of nodes invaded between 1 and 3.
N 2: cancer cells in 4 or more lymph nodes. Stages
M M x : do not know the extent of cancer.
M 0: no extension distant organs.
M 1 : no involvement in distant organs.
This system, though more correct than others, is less used because of its complexity. Which is often used is the original Dukes classification , slightly modified. Thus we have the following stages:
A: Tumor is limited to the mucosa and submucosa.
B 1 : no invasion of the muscularis propria.
B 2 : no involvement of the serosa.
C : there are lymph node metastases. C1
: nodes are involved but not serosa.
C 2 : No involvement of the serosa and lymph.
D: no distant metastases. The
five-year survival is directly related to these stages. So if the patient is in stage A has a probability of survival of 70% in the B, 45% in the C, 20% and the D, is zero.
Another prognostic factor is the symptoms. Patients who have no symptoms when diagnosed with cancer, have an 88% chance of being alive after five years. If the symptoms have been submitted three months before diagnosis, the chances drop to 40% and if it takes seven months, is only 25%. SYMPTOMS
When symptoms occur, colorectal cancer is usually advanced and the chances of survival are very slim. For this reason, early diagnosis is essential mainly based on blood loss in feces.
Patients may have any of these symptoms :
- Change in bowel habits: diarrhea, constipation or narrowing of the stool. The normal standard diarrhea that are characteristic of cancer of the cecum and ascending colon. While constipation it is located in the descending and sigmoid. The diarrhea is caused by the process irritation and constipation because the tumor is narrowing the lumen of the intestine and not allow the passage of stool.
- Sensation of having to evacuate that is not relieved by doing so.
- rectal bleeding in the stool.
- Weakness, fatigue and decreased appetite: These symptoms occur when the cancer is advanced.
- tumor mass: when the tumor is very large mass can be detected by palpation.
- cramping pain, feeling of fullness or discomfort indefinite, sometimes diffuse and sometimes localized. When an obstructive symptoms may be pain due to narrowing that occurs in the intestine. Also the pain is caused due to peri-rectal injections of nerve structures.
- Jaundice: yellowing of the skin and eyes due to liver involvement. DIAGNOSIS
1) Hemoccult fecal occult blood or
This technique can give false positives if not done correctly.
The person will faithfully follow a diet for a few days before collecting a sample.
in your diet should avoid eating raw meat or sausage for two days, and vitamin C. Are advisable vegetables, fruits and cereals.
two samples should be collected from different parts of the stool, performing the test on three consecutive days.
This test can detect a large number of cases in Stages A and B, over 84%. This test is not used as the sole method for diagnosis because it requires a colonoscopy to make a final diagnosis.
2) DRE
Physical examination performed by the doctor inserting a finger into the anus to check for abnormalities.
This technique is used as a complementary method for diagnosis is not very useful because most tumors are beyond 11cm.
3) Fibrocolonoscopy
involves inserting a hollow tube light, thin and flexible, about a finger thick. It is used to examine the colon and can also take a sample for biopsy or to make removal of polyps. This test is usually carried out with sedation of the patient to minimize discomfort.
Diagnosis involves the confirmation of the tumor and the study of the extent of it to other body organs.
diagnostic tests used are barium enema, colonoscopy, ultrasound and computed tomography. The
enema involves introducing a substance from the anus, usually barium sulfate, to fill half of the colon. The patient will move to spread the barium throughout the colon. After air is introduced to expand the colon. This is achieved by visualizing the colon by X-rays. Defects will be creases or irregular contours.
fibrocolonoscopy The direct way to view inside the colon or rectum and the lesion that is in them. The colonoscope is connected to a video camera and a monitor so the doctor can examine the intestinal tract. You can also remove polyps or collect material for biopsy. This technique is, nowadays, the best diagnostic method.
The ultrasound uses sound waves to create an image. It is useful to rule out liver or pelvic metastases. Also to know if there is local or regional invasion in rectal cancer.
The CT is an X-ray technique, which uses a rotating beam, which is displayed with different areas of the body from different angles. It is used to rule out metastasis to other organs.
laboratory data to be studied are the results of the technique of fecal occult blood, the number of red blood cells in blood, sedimentation rate and liver function tests. These data will be altered in cancer. These patients usually have anemia due to continuous loss of blood in feces.
TREATMENT Treatment is based primarily on three techniques that are surgery, radiotherapy and chemotherapy.
Surgery Surgery is the only curative treatment capacity in this cancer. With it you get a 50% disease-free survival.
The surgical technique used will depend on where you are located the tumor.
When the tumor is located in the colon, the operation is usually performed segmental resection that is removal of the tumor and a segment of normal tissue on either side of cancer.
is usually a third of the colon removed, and the amount of tissue vary depending on the size and location. The remaining sections are reattached. May, temporarily, have to perform a colostomy.
The colostomy is to join the colon to an artificial outlet in the wall of the abdomen. A bag is placed on the skin adhesive that will collect the droppings.
If the staging is very low, can be removed through a colonoscope. This technique avoids the surgical incision.
Through laparoscopy can remove segments of the colon and lymph nodes. It involves inserting a long, lighted tube, with which you look inside the abdomen through a small incision. This tube has its end few gadgets that are used to cut tissue.
tumors that are large tend to block the passage of stool, this is called a bowel obstruction. When you can not remove these tumors have to perform a colostomy to the disposal of the waste. In this case, the colostomy is permanent.
As for cancer rectum, as well the affected section will be a technique or another.
When the tumor is above 7-8 cm from the anal canal, near the junction of the rectum and colon, there will be a low anterior resection . With it will remove the part where the cancer and join the rectum to the colon.
If the tumor is located closer to the anus, the need for abdominoperineal resection . After this, it will require a colostomy because we can not get the union of the rectum to the colon.
affected
When the rectum and nearby organs, including bladder, prostate or uterus, is performed pelvic exenteration which is the removal of these organs. Also the colostomy is needed here, and if the bladder is removed, it is necessary to make a urostomy, which is to create an outlet in the abdomen for urine.
If there are metastases, as the number and location of these, you can perform an operation to remove the tumor. The surgery will be performed in those patients who will prolong their life or improve its quality.
There are other methods to remove those tumors that do not require surgery. Among others are freezing the tumor or injection of concentrated alcohol destroy them.
Chemotherapy Chemotherapy involves the administration of drugs that destroy or damage cancer cells. It is used in rectal tumors at high risk of spread in Dukes' stage C onwards.
There are several routes of administration, but the most frequent oral and intravenous.
hospitalization is not required to receive this treatment can be done on an outpatient basis. This depends on the state of the patient and duration of treatment.
chemotherapy treatment in cancer colon was performed as adjuvant therapy, ie combined with surgery.
Thanks to advances in chemotherapy treatment carried out in recent decades, the prognosis and survival of colorectal cancer has increased significantly.
These advances involve the use of several drugs combined, not each one separately.
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Radiotherapy involves the use of high-energy rays such as X rays, to destroy or reduce the number of cancer cells. Is a local treatment.
It takes place over five days a week for several weeks (the oncologist and the radiologist have believed appropriate), and the patient goes to an outpatient clinic or where they do the radiation therapy must not be entered for it.
such, the treatment lasts a few minutes. It is not painful but it is something like an X-ray radiation only is greater and is concentrated in the affected area.
side effects of this treatment are mild skin irritation, nausea, diarrhea, rectal irritation, irritation bladder or tiredness.
Radiotherapy is mainly used in this type of cancer when the tumor is attached to another organ or tissue in a way that prevents its removal by surgery.
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