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Colorectal cancer is the most common malignancy of the gastrointestinal tract and one of the tumors with the highest incidence and mortality. In developed countries, colorectal cancer ranks second in incidence, with more than 10,000 new cases per year, behind breast cancer.
He also ranks second in mortality, in this case behind lung cancer.
By Dr. Alfredo Ubaldo Gualdrini
Development (Colorectal Unit, Gastroenterology Hospital Dr. Carlos Bonorino Udaondo.)
Characteristics of colorectal cancer
Colorectal cancer has some features to highlight:
- Unlike other tumors, affects both men and women with a prevalence of 5% throughout life.
- Has a defined preneoplastic lesion, which is the adenoma and its progression is the result of a sequence of alterations in oncogenes and suppressor genes, which develops slowly over several years.
- Early diagnosis (stage I and II) allows a high cure rate, while a late diagnosis survival is less than 60% at 5 years.
- 75% of colon cancers are sporadic, meaning that develop in people with no personal or family history.
- The peak incidence is between 65 and 75 years of age.
- The duration of the adenoma-carcinoma for adenomas <1 cm in diameter, is 10 to 15 years, and for> 1 cm is 5 years.
Prevention
Primary prevention aims to identify risk factors in the diet and lifestyle to try to change them through education of the population.
Secondary prevention of CRC should be performed both in people at increased risk as in the general population (average risk). Epidemiological studies showed that the eradication of adenomas or cancer treatment in their early or asymptomatic phase is highly cost-effective, particularly in individuals with the following risk factors:
- Personal history of colorectal polyps, especially adenomas.
- Inflammatory bowel disease (ulcerative colitis and Crohn's disease non-specific).
- Personal history of colorectal cancer.
- Family history of colorectal polyps or colorectal cancer.
- A history of familial adenomatous polyposis.
- History of cancer hereditary non-polyposis colon Lynch syndrome).
However, if the research would be limited only to risk roups 25%) would leave no chance for early detection prevention to 75% of colorectal cancers (sporadic cases) on a limited impact in reducing morbidity and mortality.
Familial adenomatous polyposis
Familial adenomatous polyposis is an inherited disease that manifests from adolescence through the formation of hundreds to thousands of polyps or adenomas throughout the gastrointestinal tract, but with high prevalence in the large intestine.
In familial adenomatous polyposis research strategy depends on the availability of genetic testing, which should be performed in specialized centers.
If there is no method is indicated endoscopy. Call for mutation of the APC gene (adenomatous polyposis coli) in the index case (family member affected by the disease). If the mutation is present, which occurs in approximately 80% of cases, genetic testing is performed in relatives at risk for this mutation.
Endoscopic detection is indicated by:
- a) genetic testing is not available
- b) the index case (affected person) could not be evaluated (eg death)
- c) the family at risk is positive.
In such cases the fibrorrectosigmoideoscopía be conducted with the following range:
- Annual for 12 years.
- Every 2 years from age 24.
- Every 3 years from 34 years.
- Every 3 to 5 years from 44 years.
- After 50 years the search continues in a manner similar to the average risk.
In patients operated which underwent total colectomy with ileorrectoanastomosis should continue with annual endoscopy of the rectum.
Colorectal cancer hereditary nonpolyposis syndrome (Lynch)
A family carries Lynch syndrome when it meets the clinical criteria for Amsterdam I and its subsequent amendment in 1999 (Amsterdam II). These criteria are:
Three families affected by Lynch-associated cancers (colorectal, endometrial, small bowel, ureter and renal pelvis).
- One first degree relative of the other two.
- Two or more successive generations affected.
- At least one case diagnosed before age 50.
- Exclusion of familial adenomatous polyposis.
- Tumors verified histologically.
If clinical criteria are met Amsterdam II shows the genetic study, but if you do not have the same research should be performed endoscopically.
The endoscopic screening for Lynch is colonoscopy every 1-2 years from 20-25 years.
Inflammatory bowel disease (IBD)
Both ulcerative colitis nonspecific, such as Crohn's laenfermedad are chronic inflammatory diseases associated with premalignant potential, among other factors, the duration of the disease and the degree of colonic involvement.
In sporadic cancer is the precursor adenomatous polyp, whereas in IBD the precursor lesion is dysplasia. Therefore, the strategy for the prevention of colorectal cancer in IBD is the detection of dysplasia through the biopsies performed by colonoscopy.
4 recommended multiple biopsies (one per quadrant) every 10 cm in remission of the disease.
Not recommended in acute period of confusion that can arise between dysplasia and inflammatory changes of the mucosa.
Research is recommended colonoscopy every 1-2 years after 8 years in cases of ulcerative pancolitis and after 12 years of evolution in the left forms of ulcerative colitis and Crohn's disease.
The algorithm for IBD would be:
- Negative biopsies: continued surveillance prior annual or biennial.
- Biopsy of low-grade dysplasia: repeat study at 6 months.
- Biopsy with high grade dysplasia: total colectomy.
- Indefinite biopsy: review the sample with a pathologist and reevaluate in 6 months.
Recommendations for prevention and early detection of colorectal cancer. Argentine Consensus 2004
In all cases the choice of method should be assessed by the physician in the clinical context and according to the relative quality of study methods available
in a given community. The decision must be taken in conjunction with the patient after informing on the advantages and limitations of various options.
Colonoscopy to the cecum is the method of choice. If colonoscopy is not possible to evaluate the entire colon will be a barium enema with double contrast. Along with the colonoscopy, the CEDC and the FRSC will conduct a rectal examination. The barium enema double contrast be associated with an FRSC if necessary improve visualization rectosigmoid.
In case of total colectomy ileorrectoanastomosis indicated should be continued endoscopic surveillance annual rectal and upper digestive tract by upper GI endoscopy every 1-3 years according to the findings. It is advisable to consult specialized center.
Crohn's disease, although no firm evidence, we recommend a surveillance program using colonoscopy and moderate dysplasia biopsies for every 1-2 years from 12 years of evolution.
