Notes by dr Claudio Italiano
Colorectal carcinoma (CRC) is the most common malignant tumor originating in the colon,
rectum and appendix. With 610,000 deaths a year in the world, it is the third
most common form of cancer. We have at least 40-60 cases per 100,000 people per
year; It originates from the epithelium of the colon and begins subtly. In
general, a person begins to have strange loss anemias, with microcitemia and is
referred to the doctor for strange abdominal pain, constipation or diarrhea,
depending on whether the tumor grows in the right side (= diarrhea) or left (=
constipation), for alterations of the digestive tube that causes and consist of
narrowing or irritative action and alterations of peristalsis and of the
function of the colon. If the patient, in general, a person of 60-70 years is
addressed in good time by his doctor, the prognosis is good, provided that the
tumor has not spread elsewhere, ie metastasis to the liver and lymph nodes.
If a subject eats badly, for ex. a fleshless diet, without fiber, if it uses
meat to treat with hormones, adulterated foods, with fats, dips and sweets, with
refined sugars, if it suffers from constipation and its carcinogenic stools
stagnate in the colon, then he is predisposed to colon cancer. If in the family
the father has colon cancer, for genetic reasons the child can also be
predisposed, for a germline genetic modification, autosomal dominant with high
penetrance, with vertical transmission: in this case a simple examination of
occult blood in the stool, performed in the child, places the latter under
monitoring and protected from injury because he is controlled. If there are
doubts, the patient may be subjected to instrumental investigations, e.g.
diagnostic colonoscopy.
A neoplastic lesion of the colon, highlighted by the double contrast opaque
enema, indicated by the red arrows. Unfortunately, now unused technique
- Western diet with fats and proteins and refined sugars
- Age
- Familiarity
- CFR: colon cancer polyp digestive
It is intended as a condition for which there is a real risk of developing
cancer, compared to normal conditions.
Risk factors, therefore, include: diet, obesity, smoking, alcohol and poor
physical activity. Another risk factor is chronic intestinal inflammatory
diseases including Crohn's disease and ulcerative colitis.
Some of the hereditary conditions that can cause colorectal cancer include
familial adenomatous polyposis and non-polyposis hereditary colorectal cancer;
Colorectal cancer shows a classic example of multistep pathogenesis; this means
that in order to accumulate the mutations necessary for the genesis of invasive
carcinoma, several steps are necessary, understood as pathological moments
characterized by the acquisition of a proto-oncogene function or by the loss of
function of a tumor suppressor gene.
The genetic mutations responsible for sporadic cancer (not related to
genetically acquired mutations) of the colon-rectum, are the same as those that
characterize the inherited forms, but these conditions represent less than 5% of
the cases. Therefore, a mutation of APC or β-catenin leads to excessive
proliferation of the epithelium and an abhorrent cell-cell interaction. The
second step of the APC / β - Catenin pathway is represented by a series of
mutagenic multistep processes catalyzed by intense epithelial proliferation.
Each mutation involves a further loss of gene control (chromosomal instability),
correlating with greater possibility of mutations and evolution towards the
malignant phenotype.
The first gene to be considered is K-Ras, oncogene mutated in over 50% of colon carcinomas and responsible for the transduction of proliferation signals. In the past, particular attention was paid to the role of the DCC gene (deleted in colon cancer). The reason why the neoplasms are formed here is likely to be correlated with the fact that in the last tract of the colon can stagnate stools and, with them, the carcinogenic substances contained in the fecal scibal. Thus, 70-90% of the benign and malignant neoplasms of the colon develop in the left colon. Another important fact is that even the benign lesions have the same concentration and percentage of the malignant ones. In particular if there is an adenoma, this exposes you to the risk of developing cancer for at least 3 times and not only at the site of the lesion. For this reason, since an adenomatous polyp is visualized, at a distance it is possible to find a malignant lesion, for which we speak in jargon of "sentinel polyp", that is of an octopus that is in the vanguard to the carcinomatous lesion. Another fact to underline, from experience, is that after a polyp removal, remote follow-up is necessary, within every 6 months for the first 2 years and then an annual check.
Long history of ulcerative pancolitis: Epithelial dysplasia
Familial polyposis, Familiarity for colonoscopic ca, Colonial precgrict, Adenoma
- adenomatosis: adenoma
Adenomatous polyps, precancerous lesions
Adenomatous polyps can cause rectorrhagia and may proliferate on the outside,
but above all this type of polyp can degenerate into carcinoma, through the
stages of dysplasia and carcinoma in situ, until the malignant neoplastic cells
invade the pedicle of the same polyp and they spread .
Polyps can be macroscopically different in shape:
- 75% of cases are tubular
- 10% are villous
-in the remaining 15% adenomas-tubulovillosis
Colorectal tumors may present in vegetative form, with "cauliflower appearance",
(protrude in the intestinal canal, such as polyps), ulcerated (frequent),
infiltrating the mucosa (sharp and scarcely detected, rare margins) and
stenosing ring finger ( like a ring around the intestinal mucosa). Generally the
tumors of the right colon have more often a vegetative morphology; because of
the wider caliber of the bowel at this level, they stenose the lumen causing
intestinal obstruction only in the later stages (unless they are located at the
ileocecal valve level); however, in spite of the later onset of symptoms, they
tend to infiltrate the wall earlier than the left colon. On the other hand, the
neoplasms of the left colon give a more precocious sign of self (generally
intestinal obstruction), but tend to infiltrate the wall of the bowel with less
speed.
Histological types
The classification of the World Health Organization (WHO) suggests the
subdivision into epithelial, carcinoid, non-epithelial tumors and of the
hemopoietic system. The most widespread type is adenocarcinoma (95%), but they
also recognize:
- Epithelial disorders: mucinous adenocarcinoma, adenocarcinoma with ring-shaped
cells, squamous carcinoma, adeno-squamous carcinoma, undifferentiated carcinoma
- Carcinoids: with argentaffine or non-argentaffine cells, but also with
composite
Non-epithelial symptoms: leiomyosarcomas and sarcomas
The symptomatology of the neoplastic lesions of the left colon is very variable
and not always related to the size of the lesion. In fact it is possible that
the course is completely asymptomatic until the neoplasia reaches considerable
dimensions or even secondarisms. Symptoms most often are proctorrhagia,
sideropenic anemia, rectal tenesmus, constipation or diarrhea, hypokalemia,
spasm pain or intussusception. In general, the patient reaches the doctor's
presence due to iron deficiency anemia and asthenia, a more frequent case. Other
times for subocclusive episodes with late vomiting, as was the case of the
elderly patient referred to by the tac abdomen who was accused of long-term
constipation and subocclusion with vague abdominal pain.
Spread of the neoplasm
Lymphatic dissemination is frequent, with involvement of the epicolic and
paracolic lymph nodes. In the more advanced stages of the disease such lymph
node districts may be affected: At the rectum level there are three main routes
of lymphatic outflow:
- Upper lymph node district, connected with the upper hemorrhoidal artery
- Middle lymph node district, connected with the average hemorrhoidal artery
- Lower lymph node district, connected with the inferior hemorrhoidal artery
Blood dissemination assumes an important role because, in advanced stages of
disease, it is often possible to trace liver metastases by virtue of the narrow
portal connection between the intestine and the liver.
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TAC dell'addome, documenta una neoplasia stenosante e vegetante del colon destro all'altezza tra l'ascendente e la flessura epatica, da un mio caso clinico, operato poi con successo, paziente donna di 86 anni! |
It makes use of laboratory investigations, for example the blood count that can document anemic status from chronic loss (sideropenic anemia), the old fecal occult blood test; still a role, even if limited, carry out tumor markers (CEA, CA 19/9 - GICA) can give an idea even if their usefulness is more in the follow-up of the post-surgical monitoring. The diagnosis of colon cancer is easy, thanks to endoscopy. Colorectal cancer can be diagnosed by biopsy obtained during a sigmoidoscopy or a colonoscopy certainly among the most important and unfortunately more frequent pathologies of the colon, and especially in the left one. and radiology (opaque dual-contrast clisma and tac with contrast medium per os); once the lesion has been identified, biopsies must be carried out on site; if they are polyps, they must be removed in full, taking into account that their stalk may be affected by the extension of the cancerous lesion. There are new techniques such as chromoendoscopy that allow a more precise diagnosis and makes use of the perendoscopic use of vital dyes to contrast neoplastic lesions, both in the diagnostic and operative phases. In the case of elderly, heart patients, who can not perform a diagnostic colonoscopy, it may be indicated to perform an abdominal CT scan with a contrast agent for os and venous route. Other techniques such as abdominal resonance that allows the reconstruction of the lower tract of the digestive tube (virtual coloscopy), are considered new and unreliable techniques, especially if in the hands of less experienced radiologists: for example. it is easy to exchange a faecal scial with the intestinal lumen for a neoplastic lesion of the sessile colon.