cancer colon | Colon Cancers - Rectum

Colon Cancers - Rectum




Generality What is colon cancer? Types of colon cancerCauseEpidemiology
Generality
Colon cancer - or colon cancer or colorectal cancer - is the malignant neoplasm of the large intestine, resulting from the uncontrolled proliferation of one of the cells that make up the wall.
Colon cancer

The precise causes of colon cancer are unclear; however, the doctors agree that, on the development of the neoplasia in question, certainly affect: an unhealthy diet, cigarette smoking, obesity, sedentary lifestyle, some inherited diseases, a certain family predisposition, the presence of intestinal polyps and inflammatory bowel diseases.
Typical of old age, colon cancer is generally responsible for symptoms such as: changes in bowel habits, rectal bleeding, blood in the stool, anemia, abdominal pain, abdominal cramps, sensation of emptying of the bowel after defecation etc.
An accurate diagnosis of colon cancer requires several investigations; a fundamental diagnostic test is colonoscopy.
Among the possible treatments of colon cancer include: surgical therapy, radiotherapy, chemotherapy and so-called "targeted therapy".
Brief recall of anatomy on the intestine
The intestine is the portion of the digestive system between the pylorus and the anal orifice.
The anatomists subdivide it into two main areas: the small intestine, also called the small intestine, and the large intestine, also called the large intestine.

The small intestine is the first part; it begins at the level of the pyloric valve, which separates it from the stomach, and ends at the ileocecal valve level, located at the border with the large intestine. The small intestine consists of three sections (the duodenum, the fasting and the ileum), is about 7 meters long and has an average diameter of 4 centimeters.
The large intestine is the terminal tract of the intestine and digestive system. It starts from the ileocecal valve and ends at the anus; consists of 6 sections (blind, ascending colon, transverse colon, descending colon, sigma and rectum), is about 2 meters long and has an average diameter of 7 centimeters (hence the name of large intestine).
Functions of small intestine and large intestine in short
Small intestine

It completes the digestion of foods coming from the stomach and provides for the absorption of nutrients (about 90%).

Large intestine

It absorbs water and electrolytes from what comes from the small intestine and "prepares" the feces for expulsion.
Colon Retto
Figure: portions of the large intestine. The large intestine, or large intestine, begins with the portion of the cecum; therefore, it proceeds with the ascending colon, the transverse colon and the descending colon; finally, it ends with the sigmoid and the rectum. From the histological point of view, the colon, sigma and rectum are very similar.

What is colon cancer?
Colon cancer, or colon cancer, is the malignant tumor of the large intestine, the result of the uncontrolled proliferation of one of the cells in the layers of the inner wall of the large intestine.
In other words, colon cancer is the malignant neoplasm that develops from a "mad cell", located in the inner wall of one of the following traits: ascending colon, transverse colon, descending colon, sigma or rectum.


Clarification on the term "tumor"
The use of the term "colon cancer", to define a malignant tumor of the intestine, is not entirely appropriate (the term "colon cancer" instead is perfect). In fact, in medicine, the word "tumor" indicates any neoplasm, regardless of its benign or malignant nature.
Nevertheless, in the case of colon cancer, but also of stomach cancer or pancreatic cancer, the use of the word "tumor" is accepted without particular objections, because the latter is in the common jargon much more than specialized terms, such as for example "adenocarcinoma", "carcinoma", "adenoma" etc.

"Colon cancer" and "colorectal cancer" indicate the same pathology?
In fact, the most correct names of the neoplasm described under the names of "colon cancer" or "colon cancer" are other, namely: colorectal cancer, colorectal cancer and colorectal cancer.

However, since colon, sigma and rectum have very similar histological and functional characteristics, it is widely accepted, even by the medical community, the use of the term "colon", instead of "colon-rectum". Thus, colon cancer, colon cancer, colorectal cancer, colorectal cancer and, finally, colorectal cancer are all considered synonymous.


For the most precise ...

"Colorectal cancer" is a rather generic name, which includes three different possible neoplasia of the large intestine: colon cancer, sigmoid tumor and rectal cancer.

Typical sites of colon cancer
The most common localization of colon cancer is the rectum (about 50% of cases), followed by sigma (19-21% of cases), the ascending colon (16%), the transverse colon (8%) and the colon descending (6% of cases).

Types of colon cancer
There are several types of colon cancer.
Among these types, there is one decidedly more common and important than the others: the so-called colon adenocarcinoma.

Representing 95-97% of cases of colon cancer, this malignant neoplasm originates from the epithelial cells of the colonic mucosa of the colorectal tract or from the glands interposed between these epithelial cells.
To complete the picture of the various types of colon cancer (as well as the remaining 3-5% of clinical cases), are:
Intestinal lymphoma. Belonging to the category of non-Hodgkin's lymphomas, it is the malignant tumor of the colon that arises from the uncontrolled proliferation of lymphocytes (cells of the immune system) constituting the lymphoid tissue of the intestinal mucosa.
Intestinal lymphoma is also known as intestinal MALToma; in oncology, MALTomas are the tumors of the lymphatic system that originate from the so-called MALT lymphocytes, ie the Mucosal-associated Lymphoid Tissue.
Intestinal lymphoma accounts for 0.5-1% of colon cancer cases.
Squamous carcinoma of the colon-rectum. It is the malignant tumor of the colorectal tract resulting from the neoplastic transformation of one of the squamous cells, which form the internal lining wall of the large intestine.
Tumors similar to squamous colorectal carcinoma can also form in other organs of the digestive system, such as the esophagus.
Squamous colorectal carcinoma accounts for about 1% of colorectal cancer cases.
Gastrointestinal stromal tumor. It belongs to the category of the so-called soft tissue sarcomas and originates from one of the particular cells having the function of regulating the motility of food along the digestive tract; cells with this property are found not only in the colon, but throughout the intestine and in the other organs of the digestive system.
Gastrointestinal stromal tumor with origin in the colon constitutes less than 1% of cases of colon cancer.
Colonic leiomyosarcoma or intestinal leiomyosarcoma. Also included in the category of soft tissue sarcomas, it originates in a smooth muscle cell of the colorectal tract wall.
Colonic leiomyosarcoma accounts for about 1% of cases of colon cancer.
The carcinoid of the colon. It is the malignant neoplasm that originates from one of the colorectal cells with neuroendocrine function. In the human body, cells with neuroendocrine function are hormone-producing cells.
Belonging to the large category of neuroendocrine tumors, the carcinoid of the colon constitutes just over 1% of cases of colon cancer.
What is an adenocarcinoma?
Adenocarcinoma is a particular type of malignant tumor, which originates from the epithelial cells of the exocrine glandular organs or from the epithelial cells of the tissues with secretory properties.
Examples of exocrine glandular organs are the breasts, the pancreas or the prostate; examples of tissues with secretory properties, on the other hand, are the mucosa layers that line the inner wall of the airways, esophagus, stomach, colon or rectum.
Adenocarcinomas belong to the large category of carcinomas, malignant tumors that develop from cells of epithelial tissues.
Insights
Anatomy and physiology of the colonCauseIndestinal PumpsIndexamination of Individual RiskSymptoms and SignsDiagnosisColonscopy Occult Blood in Stool Therapy and PrognosisColectomyColostomyCity and Colon Cancer
Causes
Like most malignant tumors, colon cancer is also an abnormal mass of particularly active cells. This mass derives from a single cell (obviously of the colon) which, due to a series of mutations in its DNA, has acquired the abnormal capacity to divide and grow in an uncontrolled way.
Despite numerous research conducted so far, the precise causes behind the above mutations are unknown; however, the studies aimed at identifying them have nevertheless proved to be useful and important, as they have allowed doctors to decipher, with a good margin of safety, the risk conditions (or risk factors) of colon cancer.

Main risk factors
Going into details, the main risk factors of colon cancer are:

Familiarity for colon cancer. According to experts, people with at least two first-degree relatives affected by colon cancer would be 2 to 3 times more likely to develop the same neoplasm, compared to individuals without relatives suffering from colon cancer.
The readers are reminded that familiarity with a tumor only means that, within a family nucleus, more blood relatives have developed the same neoplasia or a very similar neoplasm.
The presence of hereditary conditions associated with the development of benign or malignant tumors along the gastrointestinal tract. Scientific studies have shown that those who carry such inherited conditions present a high risk of getting colon cancer, starting as early as 30-40 years.
The two most known and important inherited conditions associated with the development of tumors along the gastrointestinal tract are: Lynch II syndrome (or hereditary non-polyposis colorectal cancer or HNPCC) and familial adenomatous polyposis (or FAP).
Lynch II syndrome is characterized by being the potential responsible for many types of cancer, not just colon cancer; for example, it is able to cause tumors at the endometrium, stomach, upper urinary tract, ovary, etc.
Familial adenomatous polyposis, on the other hand, is characterized by hundreds of thousands of adenomas (or adenomatous polyps) along the mucosa of the colon-rectal tract of the intestine; colorectal adenomas are benign tumors that have a not inconsiderable ability to turn into malignant neoplasms.
The readers are reminded that the concept of hereditary predisposition to tumors is different from the concept of familiarity for a tumor: those who have a hereditary predisposition to tumors have, in their genome, mutations of DNA that can be transmitted from generation to generation, which favor neoplastic processes.
Inflammatory bowel diseases. These are conditions characterized by the chronic inflammation of the large intestine and the consequent alteration of the anatomical structure of the latter.
The two most important intestinal inflammatory diseases are ulcerative colitis and Crohn's disease.
Since the appearance of colon cancer is favorable conditions, the doctors recommend to those who are undergoing periodically to undergo a colonoscopy.
The presence of adenomatous polyps along the colorectal tract. The ability of adenomatous polyps (which are benign neoplasms) to evolve into malignant tumors has already been discussed, so it is not worth repeating.
Adenomatous polyp Figure: adenomatous polyp of the colon.
Medical studies have observed that the tendency to develop adenomatous polyps along the colorectal tract increases around 55-60 years; consequently, experts believe that, starting from this age, it is good practice to undergo a colonoscopy or in any case an examination for the monitoring of bowel health.
An unhealthy diet. Since the entire intestine is a fundamental organ for the transit and expulsion of ingested food, its health is strongly dependent on what is eaten.
After numerous research and clinical observations, doctors and experts in nutrition have concluded that it is harmful to the colon and promotes the appearance of tumors at the colon-rectal level a diet: rich in animal fats, red meat, low in fiber and reduced content of fresh fruit and vegetables.
Advanced age. Generally, the accumulation of mutations at the base of tumors such as colon cancer is a slow process, which takes many years. This explains why the patients of an intestinal neoplasm are more frequently people aged over 50 years.
Obesity, excessive consumption of alcohol, cigarette smoking and a sedentary lifestyle. Statistical studies have shown that obese, large consumers of alcohol, smokers and inactive people, when compared with normal-weighted individuals, non-smokers, non-smokers, and those with active lives, show a greater tendency to develop colorectal cancer.
The precise biological reasons for which obesity, excessive consumption of alcohol, cigarette smoking and a sedentary lifestyle increase the risk of getting colon cancer are unknown; however, it is good to remember that these risk factors are also included in the list of conditions favoring the formation of adenomatous polyps, along the colorectal tract, and the malignant evolution of such adenomatous polyps.
Membership in the Afro-American race. When compared to other more common breeds (eg, Caucasian or Asian), this breed shows a particular predisposition to colon cancer. The reasons behind this predisposition are unknown.
Radiotherapy in the abdominal or pelvic area. As has been known for some time now, ionizing radiation used for radiotherapy treatments is a factor favoring neoplastic processes.
Insulin-resistant diabetes. Epidemiological studies have found that among diabetics with an insulin resistance, the number of cases of colon cancer is higher than the number of colon cancer cases among non-diabetic people.
Based on extremely reliable research, 75-90% of cases of colon cancer are not related to genetic or family risk factors, but to: excessive consumption of red meat, fatty foods and alcohol, cigarette smoking, obesity, a sedentary lifestyle and the presence of adenomatous polyps.

Epidemiology
Globally, colon cancer is the second most common form of cancer among women (614,000 cases, 9.2% of all malignancies) and the third most common form of cancer among men (746,000 cases; 10% of all malignant tumors). It is good, however, to clarify that its diffusion varies, sometimes even considerably, according to the geographical area considered: for example, in countries such as the United States, Australia and New Zealand, colorectal cancer is very more frequent, than in African countries.

According to experts, the difference in the prevalence of the tumor in question, in the various parts of the world, strongly affects the diet: where there is a greater consumption of fatty foods and an insufficient intake of fiber, the incidence of cancer the colon exceeds the incidence values ​​of the same neoplasia in the geographical areas characterized by a low consumption of fatty foods (especially those of animal origin) and / or a diet rich in fiber.
Rare in young adults, colon cancer predominantly affects people over the age of 50-55; statistics in hand, the average age at diagnosis of colorectal cancer is 68 years.
As mentioned, colon malignant tumors have a particular preference for the African-American population.
In recent decades, there has been an interesting phenomenon (and explainable with the lengthening of life and improvement of the techniques of treatment): while the incidence of colon cancer has increased, the mortality rate associated with this cancer is decreased.
Epidemiological studies on the incidence of colon cancer among males and females have found that men and women fall ill more or less equally.
According to reliable studies, in Italy every year, colon cancer is responsible for 40,000 new cases among women and 70,000 new cases among men.
Colon cancer in numbers:
Globally, colon cancer affects more than a million people each year and causes the death of around 700,000 sick individuals;
Globally, colorectal cancer is the fourth most common cause of cancer death after lung adenocarcinoma (lung cancer), stomach cancer and liver cancer;
In a country like the United States, colon cancer is the third most common cause of cancer death;
The American Cancer Society estimated that, at the end of 2017, in the US, the new cases of colon cancer will be about 95,500;
Colon cancer has the highest incidence rate in Australia and New Zealand and the lowest in West African countries;
The incidence rate of colon cancer in African-American populations exceeds the incidence rate of colon cancer in Caucasian populations by 22-27% (27% for men and 22% for women) );
According to some studies, individuals born since 1990 have a double risk of getting colon cancer, compared to people born around the '50s (of the twentieth century clearly). The main reason for this change seems to be due to the greater spread of obesity;
The 5-year survival rate from the diagnosis of stage A (the least severe) colon cancer is more than 95%.
The 5-year survival rate from the diagnosis of a colon B-stage cancer is between 80 and 90%.
The 5-year survival rate from the diagnosis of a colon C-shaped tumor is about 65%.
The 5-year survival rate from the diagnosis of a D-stage colon cancer (the most severe) is between 5 and 10%.