The cancer of the colon develops starting from the mucous membrane of the large Intestin. In 70% of the cases, the tumor develops in the sigmoid (buckles located in the left iliaque Fosse) or in the Rectum. The Cancer S of the colon and the rectum being rather similar, one gathers them under the term of cancer colorectal .
Epidemiology
It is the second cancer, in term of frequency, at the woman (after the Breast cancer) and the third at the man (after the Lung cancer and that of the prostate). Cancers colics have a frequency raised in France: each day, 100 people learn that they have a cancer colorectal. More exactly, one discovers 33.000 new cases per annum, and 16.000 people die about it. In the nonsmokers, they are the second cause of mortality per cancer. The men are touched a little than the women (incidence rate of 40 and 27 for - hundred - thousand, respectively. In Africa and Asia, there are much less colorectaux cancers than in Northern Europe or the the United States (until 20 times less). Moreover, the emigrants who leave a poor country for a country where the risk is important, see their rate of cancer colorectal increasing in the 10-20 years which follow their migration. These facts suggest that the lifestyle, food and physical efforts, exploit a big role the cancer risk. This resulted in thinking that an effective prevention is possible (see low page).It is primarily about a cancer of the ripe age, nearly 85% of the case occurring after 65 years. Its frequency seems to increase.
- an unexplained slimming;
- tardily, the hepatic metastases can give a very large liver to palpation.
Clinical examination
It is, in rêgle, disappointing. The rectal examination allows, by a ganté finger introduced into the anus, to seek possible rectal anomalies. Rapid and inexpensive, this examination detects only anomalies in the neighborhoods of the rectum.Complementary examinations
Search for fecal blood
The research of occult fecal blood (see above) is made all the 3 - 5 years per Hemoccult test: One spreads out oneself a little fecal Matière over a special “paperboard”, two days of continuation. Folded, this paperboard is sent to the laboratory to detect there blood even in very minor amount. One can thus detect the bleeding of an intestinal polyp (not inevitably cancerous). If this test is positive, it is remade, and if positivity is confirmed, a Coloscopie must be made. The Hemoccult test is the 1st diagnostic tools used at the time of the tracking campaigns. However, this test has limits: the patient must abstain from eating little cooked meats, Blood pudding and any source external of blood in the three days which precede the test. He is too not very specific and sensitive at the subject considered at the risks where one prefers to propose from the start a coloscopy and does not allow to remove the polyps. If a polyp is detected, one must make a colonoscopy to remove it. The coloscanner nevertheless is preferred if the patient is regarded as fragile, because does not require a General anesthesia.Other types of examinations are used little, too expensive, too new, or not specific enough or sensitive (vidéocapsule, FART, ECA…).
Anatomopathology
The adenocarcinomists account for 95% of the cases, including 17% adenocarcinomists colloids or mucineux.
Forecast
The only classification used into preoperative is the classification TNM whose 6th version goes back to 2002.Classification TNM
T (tumor)- Tis intraepithelial or chorion
- T1 musculeuse submucosa
- T2
- T3 through the muscularis propria under-séreuse or in not peritonealized fabrics pericolic.
- T4 body or structure of vicinity and/or perforation of the visceral peritoneum
- ganglionic N0 not of Metastasis
- Nx not evaluated ganglia or less than 8 examined ganglia
- N1 1 to 3 regional metastatic ganglia
- M0 not of metastasis
- M1 remote metastases (of which known-claviculaires ganglia)
Stadification
From the data of classification TNM, cancers of the colon are classified in 4 stages. The chances of cure vary considerably stage I at the stage IV. For each stage is noted between brackets the rate of survival five years after the treatment. The therapeutic strategy is also adapted to each one of these stages.- Stage I (93.2%): pT1-T2 N0 M0
- Stage II: pT3-T4 N0 M0
- Stage IIA (84.7%): pT3 N0 M0
- Stage IIB (72.2%): pT4 N0 M0
- Stage III: all T N1-N2 M0
- Stage IIIA (83.4%): pT1T2N1M0
- Stage IIIB (64.1%): pT3T4N1M0
- Stage IIIC (44.3%): all T N2M0
- Stage IV (8.1%): remote metastases
The forecast is worse in the event of occlusion or of perforation, of cancer mucous or undifferentiated colloid. It is better in the event of phenotype RER+ (MSI).
Treatment
When cancer is detected at an early stage, it is cured (90% of cures for stages I). If cancer is tardily discovered, the chances of cure are much weaker (less than 5% of cure at the stage IV). The first treatment is the Chirurgie, which makes it possible to remove the surrounding tumor and ganglia (ganglionic clearing out). (Very surface cancers are sometimes completely réséqués by endoscopic way, without complementary surgery necessary if there is not crossing of the muscular mucous membrane). One associates auxiliary treatments with it: Chimiothérapie, if the clearing out contains ganglionic metastases or if there exist hepatic or pulmonary metastases; Radiotherapy if the surgical exerèse could not be total, with tumoral remainder individualized on a vital body.In the case of the cancer of the low rectum, the presence of visible ganglia on the scanner or the echoendoscopy are a preoperative indication of radio-chemotherapy.
Therapeutic methods
Endoscopy
Any polyp removed in endoscopy is studied in pathological anatomy. The presence of dysplasy (précancéreux state) or very surface canceration (not of invasion of the muscular mucous membrane) made that the endoscopic résection is curative. The presence of cancer on a bank of exérèse or an invasion in-depth involves an indication of complementary surgery systematic (except if the general state of the patient does not allow it).
Surgery
The goal of the surgery is to remove the tumor and the ganglia which are around by ganglionic clearing out. The ganglia accompanying the blood-vessels irrigant the colon (located in the mésocôlon, lubricating blade extending between the aorta and the colon), one is thus to remove a segment of colon and not simply the tumor. The exérèse, to be sufficient, must carry at least 5 cm of colon on both sides of cancer, and at least 12 ganglia in the clearing out.Because of vascular anatomy of the colon, the interventions most usually practiced are:
- right hemicolectomy, with anastomosis iléo-transverse, carrying all the mésocôlon to the flat rim of the higher mesenteric artery;
- the true left hemicolectomy, with anastomosis enters the transverse colon and the high rectum. The ganglionic clearing out carries the lower mesenteric artery, related to 1 cm of its origin on the aorta and its branches. ;
- sigmoidectomy with vascular binding after emergence of the left artery higher colic;
- the résections of the transverse colon are atypical and depend on the vascular anatomy highlighted into preoperative.
These interventions can be made by laparotomy (opening of the belly) or by Cœlioscopie (one works in a belly inflated by CO2 thanks to instruments introduced by openings of 1 cm. Cancer left by a small incision at the end the intervention).
The résections of a cancer of the rectum require to remove all the ganglionic surface périrectale (mésorectum) and to ensure a ganglionic clearing out in the lower mesenteric surface, preserving the left artery colic or not.
The presence of a noncurable anal incontinence, complications of cancer with type of occlusion or perforation, or impossibility of preserving the anal sphincter, result in practicing a Stomie (or artificial anus): the colon is brought together with the skin of the abdomen, and the saddles are recovered in a pocket which the patient positions itself the every day or every 3 days. The currently available equipment ensures a comfort of quality.
If it discovered hepatic metastases there during the surgery of a cancer of the colon, the résection is considered: in a synchronous way (in same operational time) if the exérèse appears easy, in way métachrone (later) in the event of multiple metastases. Recent studies showed that the size and the number of lesions had little influence on survival after surgery. Certain techniques like the preoperative échograpie, chemotherapy néoadjuvante (before the hepatic surgery) as well as the embolisation of the branch of the dead vein of the segment reached, the radio frequency, make it possible to increase the number of operable patients their metastases and the precision of the surgical gesture.
If the patient is not operable, of the alternatives exist: Chemotherapy or more recently the application of physical treatments on metastases (ablation by radio frequency, heat treatments). Pulmonary metastases of a cancer colorectal must they also be operated when it is possible. In the contrary case, here also physical chemotherapy and treatments are possible.
Chemotherapy
The Chimiothérapie consists in managing with the patient a drug Cytotoxique intended to kill the cancer cells. This treatment, when it is effective, can eliminate metastases or prevent their appearance and/or narrow the tumors or slow down their growth. Chemotherapy is generally an auxiliary treatment carried out in addition to surgical operation to increase the chances of success. Sometimes also the treatment is palliative when the surgery is impossible, or makes it possible to decrease the size of the tumor before the operation (néo-additive).The most used drugs are:
- the 5-fluorouracile (5FU), it is the drug of reference in intestinal cancerology. There also exists in oral form (Xéloda®)
- the Oxaliplatine (LOHP) is synergistic 5FU; it is a major drug in the treatment of the cancer of the colon. At the metastatic stage, it is used associated with the 5FU (Protocol FOLFOX) and sometimes with Avastin (FOLFOX-Avastin). In second metastatic line, after a first line of chemotherapy containing Irinotécan, FOLFOX-Avastin association is more effective than the FOLFOX alone. In auxiliary situation, after a surgery of éxérèse supplements, the FOLFOX4 for 6 months is more effective than a chemotherapy containing 5FU (LV5FU2 or Fufol). The results brought up to date in 2007 of study MOSAIC show:
- six years after the surgery for a cancer of the colon of stage III, 73% of the patients treated by FOLFOX4 in life against 68.6% of the patients are treated by LV5FU2. On the other hand, there is no advantage for the patients treated for a cancer of stage II
- 5 years after the surgery, at the patients treated for a cancer of the colon of stage III or of stage II (with factors of bad forecast) the rate of relapse is weaker with the FOLFX than with the LV5FU2.
- Irinotécan® (CPT-11) can have serious side effects, severe diarrhea in particular. (inhibiter of the topoisomerase 1, not recognized by the MDR)
- the raltitrexed (Tomudex®), can involve neutropenias
- the Cetuximab (Erbitux®) is generally a monoclonal anticoprs which blocks the action of the Récepteur with the EGF, that Ci being present at the surface of the cells of the skin (from where its name), but also at the surface of the cancer cells. It significantly improves the forecast of certain cancers of the colon, even if the profit remains, however, weak (a few months).
There currently exists in France two drugs " spécifiques" given in partnership with the 5-FU: Erbitux® manufactured by the German laboratory Merck and Avastin® (laboratories ROCK). One 3rd drug which received the marketing authorization in the United States will arrive soon to France: Vectibix® (laboratories AMGEN). These three molecules are known as " antibody monoclonaux" and are close in their action since they inhibit the cellular action of the growth factors. Avastin® blocks the signal of proliferation of the néo-vessels irrigating the tumors (it blocks the neovascularization). By preventing the appearance of these vessels, one decreases the blood contribution towards the tumor, therefore his development is limited. Moreover, it would seem that these molecules increase the effectiveness of chemotherapies. The side effects are less heavy than conventional chemotherapies. Erbitux® has as a principal side effect the appearance of a pseudo-acnéique cutaneous rash (which often marks the effectiveness of the treatment) just as Vectibix® to which the mechanism of action is very close (anti EGFR). Avastin® as for him can cause more or less important bleedings as well as delays of cicatrization (it must be stopped two months before an intervention). These antibodies, because of their composition, however have an allergic accident risk (shock anaphylactic) despite everything very weak. Indeed, they are produced starting from antibodies of animal origin, generally, which are then " humanisés" , from where the allergic risk. It is not the case of Vectibix®, because it derives from antibody of human origin: there are thus no risks of allergy.
Radiotherapy
One irradiates sometimes the tumor to kill the cancer cells, before or after surgical operation. The Radiothérapie can be associated with a chemotherapy which sensitizes the tumor with the effect Létal of the rays. The radiotherapy is generally used for cancers of the rectum, sometimes into preoperative. In cancers of the colon, it can be useful if cancer cannot be réséqué entirely because of an invasion (uretère, vessels iliaques).
Nutritional support
Any résection of a cancer of the colon can involve diarrheas, sometimes invalidating. In the same way, chemotherapies used often cause an acceleration of the transit. The patients thus see themselves proposing a mode without more or less restrictive residue: to avoid eating crudenesses, vegetables rich in fibers or sauce meats can improve comfort of life. In the same way digestive thickeners Smecta type or speed reducers of the standard transit Lopéramide can help.
Psychological support
See the article Cancer > Psychological support.Therapeutic strategy
Cancer of the colon localized
Cancer of the colon or the metastatic rectum from the start
Cancer of the colon or the rectum secondarily metastatic
Colorectal cancer prevention
The majority of cancers of the colon and the rectum could be avoided by an heightened surveillance, a suitable lifestyle and, probably also, the oral catch of products of Chimioprévention.-
Monitoring: the majority of colorectaux cancers are born in Polype S (or adenomata). These lesions can be detected and removed at the time of a coloscopy. Studies show that this procedure could decrease by 80% the risk of died by intestinal cancer if one began the examinations around 45 years, then all the 5 or 10 years.
- Lifestyle: the comparison of the incidence of cancer colorectal in various areas of the world suggests that sedentariness, the excess of introduced calories and perhaps also a mode too rich in red Meat and Charcuterie S, could increase the cancer risk. Conversely, the Physical-activity and a mode rich in Fruit S and Vegetable S, would cause a drop in the cancer risk, probably because the plants contain protective micronutriments. By changing his lifestyle, one could thus decrease the cancer risk from 60 to 80%. In addition, a food supporting the fruit and vegetables, fish and the poultries, could decrease the risk of repetition and the mortality of cancer.
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Chimioprévention : more than 200 products, in particular the micronutriments quoted above, as well as other nutrients like the Calcium or the Folic acid (a Vitamin B), and drugs as the Aspirine inhibit carcinogenesis in models preclinic (in the animal). In certain studies, one completely inhibits the tumors induced chemically in the colon of the rats. Other studies show the important inhibition of the spontaneous intestinal polyps in transferred mice (Min mouse). The clinical trials of chimioprévention at human volunteers had less success, but few products were tested to date. Supplements of calcium or aspirine given each day during 3 to 5 years after the removal of a polyp, decreased the reappearance of the polyps at the volunteers (from 15 to 20%). The database of chimioprévention of the INRA gives the results of all the studies published on the agents of chimioprévention at the man and the rodents.
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