The predisposing causes for the colon neoplasm are:
- colocrectal polyps
- familial colic polyposis
- inflammatory bowel disease
- familial predisposition
- Lynch syndrome
Colorectal polyps represent a frequent situation in the gastroenterological practice, almost 10% of people 50 years - old and up to 30% of people over 70 years present colonic polyps. These polyps may be adenomatous (adenoma) and hyperplastic.
Adenomatous polyps (real polyps) are of many histological types: tubular, tubulo - villous and villous. The villous polyps have the most increased potential of malignity. The hyperplasic (inflammatory) polyps have no malignant potential.
The evolution of polyps towards malignity seems to be linked to genetic factors (familial), metabolic factors (the co- carcinogen effect of billiary acids) and alimentary factors (the negative effect of lack of vegetables and fibers). The bigger the polyps are (generally over 2 cm diameters), the more numerous and the more severe dysplasia is found at biopsy, the highest is their malignant potential. Starting from these data concerning the relationship polyp - neoplasia, searching polyps by colonoscopy and the endoscopic polypectomia has become a necessity, because it is the best prophylaxis of rectocolic neoplasia.
Familial colic polyposis represents a pathological situation with a genetic character, defined by the presence of more than 100 polyps in the rectum and colon, appearing before the age of 30 years. The genetic transmission is autosomal - dominant and the evolution of polyps to cancer is the rule. Therefore, it becomes a necessoty to check - out actively the transmission is autosomal - dominant and the evolution of polyps to cancer is the rule. Therefore, it becomes a necessity to check - out actively the transmission in the affected families and the most precociously total colectomy, before the malignization.
Inflammatory bowel diseases with prolonged evolution increase the risc of colon neoplasm. This risk is of approx. 10% after 25 years of evolution in ulcero - hemorrhagic rectocolitis (becoming significant after more than 10 years of evolution). The risk is smaller in Chron's disease with prolonged evolution.
Familial predisposition represents an increased risk for the descendants of a family with colon cancer (the frequency of cancer is 2-3 times bigger in first - degree relatives).
The Lynch syndrome or the hereditary nonpolypoidal colorectal cancer (without the intermediate state of polyp and with important hereditary involvement) is characterized by presence in more members of a family, the apparition of cancer at young age and frequently associates other neoplasms (the most eften ovary and endometer).
The Amsterdam criteria for diagnosis of Lynch syndrome are at least 3 members of a family with diagnosis of colonic carcinoma, one of which must be a first-degree relative, in a generation; the transmission be done at two succesive generations and at least one of the casees to be diagnosed before 50 years.
The differential diagnosis problems in colon cancer depend upon the differentiation of rectal bleeding. The main causes are:
- hemorrhoidal disease and anal fissure
- Chron's disease
- ulcerative colitis
- colonic diverticuli
- ischemic colitis and irradiation colitis
- colonic angiodysplasia
In front of an anemic syndrome, it should be controlled if the anemia is by iron deficiency, and in this case, the most probable and most evidently it is related to the digestive tube (esogastric, intestine or colon).
Evolution of colon cancer
The evolution of colon neoplasia depends of the moment of its discovery and operation. On the Dukes A stage, the 5 years - survival is about 90%, and in Dukes C approx. 50%. In front of a neoplasm with hepatic metastases (Dukes D), the survival is very low.
Complications of colon cancer
The most frequent are: metastases, intestinal occlusion and perforation.
Colorectal cancer represents a public health problem, considering that in most European countries it is the first on the list of neoplasms. Even if the bronchopulmonary neoplasm is prevalent in men and the genital tumors in women, totalizing their prevalence on both sexes makes the colorectal cancer the first cause of malignancy in many states.
Epidemiology
In France the incidence of colorectal cancer is 15% of all cancers, in Romania it is the first among the digestive cancers. Its frequency varies with the geographic area being very frequent in Europe and USA but less frequent in South America and Africa. These geographic differences are firstly related to the alimentary habits and in a certain measure to genetic factors.
The special problem in this cancer is that it is somewhat forewarned, since at this moment the filiations is clearly established (adenoma carcinoma), thus the endoscopic finding an will prevent the apparition. The role of genetic factor (Lynch syndrome) in the apparition of colon neoplasm is also known.
Etiopathogenesis
More factors are involved in the producing of colon neoplasm:
- the role of alimentary factors
- the role (controversial) of billioary acids
- the role of predisposing causes
a) Alimentary factors are involved in the etiopathogenesis of this neoplasia (based on epidemiologic studies), the vegetables, fibers diet, calcium and vitamins are considered as a protective diet. Negative alimentary factors are the considered as a protective diet. Negative alimentary factors are the excess of animal fats and proteins, red meat, alcohol and excessive caloric intake.
b) The role of billioary acids in the etiopathogenesis remains controversial, but there are experimental studies showing their involvement. Some epidemiologic and clinical studies have shown a relationship between cholecystectomy and the increasing of frequency of the colon neoplasm.
c) The predisposing causes for the colon neoplasm are:
- colocrectal polyps
- familial colic polyposis
- inflammatory bowel disease
- familial predisposition
- Lynch syndrome
Colon Cancer Treatment
The treatment of colon neoplasia is surgical. The intervention should be done as soon as possible, its type depending on the tumor location. The preoperatory evaluation will include the evaluation of lymph node extension and of metastases (pulmonary, hepatic or peritoneal). The postsurgical chemotherapy is indicated to patients in stages Dukes B2 and C. Schemes including 5 fluoro-uralic, asociated with folinic acid are used. considering the increasing survival postchemotherapy, it is indicated that, after surgery, the patient is sent to continue the treatment to the oncologist.
Fig.1 Colon Cancer
Radiotherapy is addressed especially to the rectal cancer, which, by its position in the small pelvis, cannot always be correctly eliminated.
The prophylaxis of colonic cancer represents an actual requirement of the medicine, regarding the place ranked by this neoplasia in the world.
- primary prophylaxis consists in measures of nourishment education, over a big number of years trying to educate the population to consume mostly vegetables, a fibers - rich diet (whole meal, cereals), calcium and to reduce the fats, the protein excess (especially red meat).
- seccondary prophylaxis consists the removal of causes that might lead to a colonic neoplasm, especially the discovering of polyps and endoscopic polypectomia. The discovering of polyps in general population is quite difficult because of the immense number of endoscopic explorations that should be done. Therefore, tests type Hemoccult are recommended followed by colonoscopy in the persons found positive. The prophylactic colonoscopy must be also performed in persons with high risk of cancer: inflammatory bowel diseases, descendents of persons with colon cancer, colonic polyps history.
The molecular screening will represent in the future the ideal method of secondary prophylaxis, by noticing the genetic mutations predisposing to colon cancer.
After the surgical resection of a colon neoplasm, CEA may be used to show the possible local recurrences. The ultrasonography and CT for possible hepatic metastases are also useful.
