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Diseases: Cancer of the rectum and colon.
Actual problems of the rectal and colon cancer.
Presently, cancer of the colon and rectum is a global problem without exaggeration. The most common cancer among men is
lung cancer, among women – breast cancer. Prevalence of rectal and colon cancer increases constantly (now this cancer is on
the second position). This tendency is the most evident in the industrial developed countries. Life style of these countries
becomes more and more popular all over the world (and also diet, as its important part). Most of scientists relate incredible rise
of colorectal cancer incidence and mortality with this factor. There are some examples to show the level of problem. Every year,
circa 1 million of new cases of colorectal cancer is detected in the world, more than 150 thousands of them in USA. In this
country 55 thousands of patients with colorectal cancer dies annually. European union, Russia have the same tendency (in
1997 year morbidity was 16,2 of cases per 100 thousand of people). In the biggest cities (Moscow, St. Petersburg) morbidity is
much higher (30,3 and 33,6 respectively). Financial expense for colorectal cancer treatment in United States total 6,5 billion
dollars per year.
In Ukraine in 2007 year morbidity of colon and rectal cancer was 38 of cases per 100 000 people (as high as in Europe).
What is the reason of colon and rectum cancer and why it appears? The answer is complicated. There are some factors, which
have the biggest influence on colorectal cancer morbidity: diet, lifestyle, urbanization. The level of rectal and colon cancer
morbidity is not the same in different countries. For example, in Western Europe and USA there are 30-40 of cases per 100 000
people, instead in Africa and Asia this mark is much lower, just 3-4 cases per 100 000 people. This fact was studied by many
scientists and they found that, in this case race is not important, for instance, immigrants from Asia and Africa had as high
colorectal cancer morbidity as native population where they emigrate. Which kind of diet is character for countries with high level
of colorectal cancer morbidity? Firs of all it is overeating. In these countries people also eat a lot of animal fats and meat. All
these factors increase the risk to get colon or rectal cancer. Instead, high fiber diet that is popular in African and Asian countries
decreases this risk. Scientists proved that dietary fat enhances bile acid synthesis by the liver, resulting in increased levels of
bile acids in the colon. When acids upon by anaerobic colon bacteria, these compounds are covered to secondary bile acids,
which are promoters of carcinogenesis. There are also proved inheritable factor in cancer beginning. Some genetic abnormalities
in colonocytes lead to loss of control over DNA repair, cell growth, differentiation and death. Usually colorectal cancer begins as
an adenoma (which can exist as a polyp many years before malignancy). Polyps are classified by dimensions, by shape and
histology. These adenomas by there histological structure can be tubular, tubulovillous and villous. Frequency of there
malignancy is 5%, 23% and 40-45% respectively. Index of malignancy sporadic polyps is 2-4%, multiple polyps (more than 2)
– 20%. Dimension has the same influence. If villous adenoma is less than 1cm, the frequency of malignancy is circa 10%, when
this adenoma is bigger than 2cm, the frequency is 53%.
Risk factors for colorectal cancer
- The age of patients (older than 50 years)
- Special diet
- Genetic syndromes: familial adenomatous polyposis (FAP), hereditary nonpoliposis colorectal carcinoma (HNPCC).
- Big adenomas
- Ulcerative colitis
- Colorectal cancer
- Family history of colorectal cancer
- Breast or genitals (for women) cancer in the past
Patients with chronic colitis, especially with ulcerative colitis, Crohn’s disease have much higher than average risk. Long
duration of colitis increases the possibility to get colon or rectal cancer (up to 5 years – 0-5%, up to 15 years – 1,4-12%,
up to 20 years – 5,4-20%, 30 years – 50%).
Screening for colorectal carcinoma
As early tumor is found as effective will be treatment. There is one of the most important principles of oncology. It works
as well with colorectal cancer. Polyps of colon and rectum and also early carcinomas are asymptomatic. The cheapest and
simplest method to fine them is fecal occult blood test (FOBT). The concept of detection carcinomas of the colon and rectum
by tasting for blood in the stool (mostly, that is so small amount of blood, that it can not be detected visually) based on the
surveillance that carcinomas bleed more than normal mucosa. Examinations of theoretically healthy people showed that
3-6% of them had positive fecal occult blood test. 10% of them had cancer; 20-40% of them had polyps. 50-70% of tests
showed false positive result. Even if this test is low specific but its using can decrease colorectal cancer mortality for 30%.
One test costs 15$. Other method of early colon and rectal cancer diagnostic is colonoscopy. 80% of patients with first stage
of cancer can be identified by this method. Well-time endoscopic polypectomy prevent there malignancy. Endoscopic
treatment of early adenocarcinomas is also high effective (15-year survival for patients with first stage is 90%). Fecal occult
blood test is recommended 1 time per year, colonoscopy – 1 time per 3-5 years for people older than 50. Equipment for
colonoscopy improves constantly. Videocolonoscopy has some advantages, one of them is the possibility to save and archive
information. Small polyps (0,1-0,2cm), which can not be identified by standard colonoscopy, can be found by
chromocolonoscopy. Endoscopic mucosectomy is a new technique that was devised especially for there excision.
Another direction in early colorectal detection is measurement of carcinoembryonic antigen (CEA). Elevated levels of CEA
(more than 6mcg/litr) were detected in blood of patients with colon, rectal, breast and womb cancer. Study of Russian
scientists detected increased level of CEA in 38% of patients with polyps (its level measured up the size of polyp and degree
of dysplasia). For example, increased level of carcinoemryonic antigen was defined in 52% of patients with first and second
stage (UICC classification) and in 100% of patients with fourth stage. Measurement of CEA is used also for observation
patients with colorectal cancer after operation. Quick increase of CEA can evidence about local recurrence or metastasis.
Clinical features of rectal and colon cancer
The most common symptoms for rectal cancers are bleeding, bowel movement disorders and stomachache. Bleeding or
presents of occult blood in the stool are the symptoms, which are presented almost in all patients with cancer of rectum.
Scarlet color of blood is typical for cancer of anal canal and rectum. Instead, dark color of blood is typical for left colon
cancer. Herewith, when blood is mixed with feces it is more specific symptom for cancer. Occult blood in the stool (when
blood can not be detected visually), anemia, weakness are the symptoms more representative for right colon cancer.
Bowel movement disorders (mostly, straining during defecation) are specific for advanced left colon and rectal cancer.
Some patients with colon and rectal cancer first present, as surgical emergency, with intestinal obstruction and need
The most common complaint of patients with rectal cancer is sensation of incomplete evaluation. Stomachache can be
absent. Patients have weakness, lose appetite, and weight. Increment of liver usually is the symptom of advents cancer.
Diagnosis of rectal and colon cancer
Presently, examination algorithm of all patients with symptoms of intestinal dysfunction and rectal bleeding should include
digital examination, endoscopy (rigid sigmoidoscopy, colonoscopy, gastroscopy), ultrasonography and X- examination of
lungs. All found tumors should be identified histologically. Double-contrast barium enema is necessary to specify tumor
localization and extension, degree of intestinal stricture. Endorectal ultrasonography is obligate examination to define stage
of rectal cancer. If doctor has any reason to suspect metastasis computed tomography (CT) should be applied.
Algorithm of rectal cancer diagnostic
1. Analysis of complaints and anamnesis (people older than 50 have much higher risk of rectal cancer).
2. Clinical examinations
3. Digital examination of rectum
4. Rigid sigmoidoscopy
5. Fecal occult blood test
7. Double-contrast barium enema
9. Endorectal ultrasonography
10. Biopsy of found tumor
Classification of rectal and colon cancer
TNM staging is the most common classification for the rectal and colon cancer.
T – primary tumor
N – regional lymph nodes
M – distant metastasis
Tx- primary tumor can not be assessed, T0 – no evidence of primary tumor, Tis – carcinoma in situ, T1 – tumor invades
submucosa, T2 – tumor invades muscular propria, T3 – tumor invades through the muscularis propria into subserosa or into
nonperitoneal pericolic or perirectal tissues, T4 – tumor perforates the visceral peritoneum or directly invades other organs
Nx – regional lymph nodes can not be assessed, N0 – no regional lymph node metastasis, N1 – metastasis in one to three
pericolic or perirectal lymph nodes, N2 – metastasis in four or more preicolic or perirectal lymph nodes.
Mx – presence of distant metastasis can not be assessed, M0 – no distant metastasis, M1 – distant metastasis
Duke’s classification is also very common. There are A, B, C and D stages.
A – tumor doesn’t invade serosa, B – tumor invades serosa, C – metastasis in any regional lymph node, invasion of tumor
is not important, D – any tumor dimension with distant metastasis.
The most common complications of rectal and colon cancer are: intestinal obstruction, intestinal bleeding, perforation in
cancer area or in the distended colon proximal to the obstruction cancer. Anemia is typical for right colon cancer.
All complications need spatial treatment. For example, strong bleeding, acute intestinal obstruction, perforation require
Patients with advanced cancer can have combination of complications, that evidently aggravate result. Well-timed diagnostic
is the prophylaxis of complications.