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Colon Cancer

 

Malignant tumours of the large bowel

 

The most frequent malignant tumours of the large bowel and the rectum

In medicine, one principally distinguishes between primary and secondary tumours (metastases). A primary, i.e. malignant tumour in the large bowel is a tumour that develops in the colon or rectum and has the characteristic of producing metastases. The metastases of these tumours are flushed into the liver via the lymphatic system and then into the lung, where they will go on growing. The most frequent tumour in the large bowel is the adenocarcinoma, which emanates from the mucous membrane of the large bowel. If the same tumour is found at a distance of 16 cm from the anus, it is called carcinoma of the rectum. Other and rarer carcinomas that are found are called mucigenous adenocarcinoma or signet ring cell carcinoma. The exterior shape, which the tumour takes in the colon, can also be very different: it may be stalked, it may grow diffusely or ring-shaped and thus narrowing the diameter of the colon. Depending on the form of their appearance, the early symptoms accompanying this tumour are also very different. The causes for the formation of these tumours are not exactly known. Under discussion are genetic factors, but also eating habits like the consumption of food rich in fats. Some risk factors are, however, well known. Among them are certain preceding diseases of the colon, as for instance the ulcerative colitis, Morbus Crohn, or familial poliposis coli. The latter is supposed to be a precancer (preliminary stage of tumour) because the many proliferations of the mucous membrane of the colon (polyps) become malignant after a certain time. If near relatives have already suffered from a carcinoma of the colon, the probability of obtaining such a tumour is also increased.

How do I recognize a malignant tumour of the large bowel?

Unfortunately, the first symptoms with patients suffering from this tumour are very different or not extant at all. If the diameter of the colon is narrowed in by the tumour, problems with the action of the bowels may result (diarrhoea alternates with constipation) or colicky pains and flatulence. Stalked tumours are prone to bleed more often and thus may cause an insidious anaemia in the patient. If bleeding is discovered at the anus or in the stool, the patient should immediately consult a doctor to clarify whether this has only to do with a haemorrhoidal disease or if there are other causes.

Necessary clarifications and diagnostic possibilities

Unfortunately, various diseases of the colon or stomach may cause the above-mentioned complaints, so that the doctor first has to ask about the precise course of the clinical history: Since when have the pains or irregularities of stool occurred? Do the pains have a connection with certain food or the intake of food as a whole? Is there any significant loss of weight and an obvious loss of fitness? Also questions about blood in the stool or apposition of blood on the stool are very important. Are there close relatives, who suffered from special diseases of the colon or who had a carcinoma of the large bowel? In this case, the doctor will examine the abdomen and feel whether there is excessive flatulence, whether a tumour can be palpitated, or whether there are hernial canals. A laboratory test is certainly carried out to get an overview of the functions of all organs and to exclude anaemia. As the greater part of the carcinomas is found in the rectum, a digital examination of the rectum by the doctor is very important as soon as there is the slightest suspicion that a tumour might be in this area. If the suspicion of a carcinoma of the colon or rectum has been confirmed, an endoscopic examination of the rectum and the large bowel has to be made, and samples of the tissue must be drawn from all suspicious spots of the mucous membrane. Further, an ultrasound examination of the abdomen will be made to assess the liver (metastases?), gall bladder, bile ducts, pancreas, and kidneys. Depending on location and size of the tumour and on other accompanying diseases of the patient, special examinations may become necessary, for instance a CT examination, endosonography of the rectum (the exact location of the tumour is important for the planning of the operation), an ultrasound, or a diagnosis of the pulmonary function.

How can a colonrectal carcinoma be treated?

Has the diagnosis of a carcinoma of the colon or rectum been confirmed, a surgical removal is the therapy indicated. It may definitely relieve the patient from his tumour disease, depending on the stage of the tumour, however. Conservative therapies like chemotherapy are only used complementarily. Before the operation, the colon is flushed to avoid infections through germs during the removal and joining together of the colon. For the very same reason, every patient receives antibiotics before the operation, which is continued afterwards for some days. The objective of an operation of the large bowel is the removal of the section of the bowel infested by the tumour and of the lymphatic nodes belonging to it, as well as the re-anastamosis of the great bowel (anastamosis: joining of hollow organs). In this case, the location of the tumour does not matter.

In the following text, a hemicolectomy (right side) will be described as an example: If this operation is carried out, the tumour is found somewhere in the ascending part of the large bowel on the right of the "frame" (see above). The surgeon accesses the abdominal cavity by an incision, beginning a few centimetres above the navel, turningleft and further down until the pubic hair line. Then, the abdominal wall is severed and the abdominal cavity is opened. The surgeon assesses all organs, liver, spleen, and stomach with his hand for the sake of orientation. He wants to find out whether there are enlarged lymphatic nodes or metastases. Then, he looks for the ascending colon on the right side and for the appendix (caecum), which is the section of the large bowel into which the small bowel empties. If the tumour is found very close to the place of this juncture, the surgeon has to be very careful as to how much of the small bowel he removes, because it is at the point where a lot of bile acid is absorbed. Then, the surgeon will demarcate the spots where he will sever the colon, guided by the location of the tumour. The suspensory ligaments between the large bowel and liver and large bowel and stomach have to be cut. As parts of the ascending large bowel are fixed to the peritoneum, it is carefully detached from its surrounding and mobilized towards the middle of the abdomen. Special attention has to be given to the urinary duct, which is found in the peritoneum at the back. The next step is to carefully expose the vessels in their band of tissue, which run from the middle of the abdomen to the outside, and the large bowel. The necessary distance to the tumour must be kept when the bowel is clamped off at both sides. The already exposed vessels are tied, and the bowel is cut at both sides and removed. The remaining stumps are disinfected, and the large and the small bowel are carefully stitched together. A silicone drainage is placed near the anastomosis and separately conducted to the outside. After checking that there are no bleedings, the abdominal wall is closed layer by layer. If a tumour is located in the diagonal or descending part of the large bowel, the surgical proceeding is the same, again under special consideration of the blood supply and other details.

The proceeding becomes more complicated if the tumour is found in the rectum because here, the colon is already located in the small pelvis and, therefore, surgical access is more difficult. The curative treatment of a carcinoma of the rectum is carried out through an anterior rectectomy. Access to the abdominal cavity is achieved in the same way as in a hemicolectomy. Then, the surgeon turns to the left side of the lower abdomen to locate the section of the bowel with the tumour. From the preliminary examination, the surgeon will usually know where the tumour will be found. This is especially important in the case of a tumour of the rectum because the distance of the tumour from the anus plays a great role for the planning of the operation, even more so for the realization of the anastomosis in this area. In order to be able to excise the bowel near the rectum, the preceding part of the bowel (colon descendens) must first be detached from its bed and mobilized. Depending on the size of the tumour, the pertinent lymphatic nodes are dissected from the great vessels and removed. The vessels coming from middle of the abdomen in a cord of tissue are exposed and removed. Then, the rectum, which lies in the small pelvis, is mobilized. In this phase, the surgeon has to be very careful not to injure the two urinary ducts. The rectum is located in a suspensory ligament surrounded by fatty tissue (mesorectum), in which the vessels and lymphatic vessels are placed. The mesorectum is thoroughly removed to eliminate possible metastases: This modern surgical method (TME, total mesorectal excision) was introduced by Professor Bill Heald in 1985. The section of the bowel with the tumour is removed along with the pertinent suspending ligaments (mesenteries), the tumour-infested lymphatic vessels, and the lymphatic glands. Near the place, from where part of the rectum has to be removed, the nervi cavernosi are located, which are important for male potency. Thanks to this technique, they can be preserved in practically all cases. The next step is to restore the continuity of the bowel. For this purpose, the most modern linear stapling devices are used. They make anastomoses of the bowel possible, even if there is only a distance of a few centimetres from the anus. This had not been possible until a few years ago, so that patients had to live with an artificial anus (anus praeter). Today, only one out of five patients has to live with an artificial anus. The final proceeding is to control whether there is any bleeding, to install a silicone drainage, and to close the abdominal wall layer by layer.

Eventually, two surgical measures should be mentioned, which are only used in very special situations. One of them is the ileotransversostomy, which is carried out in the case of big tumours that narrow the right colon. The tumour is so to speak bypassed in the process. The small bowel is sutured side by side to that part of the transverse colon, which is located further down from the tumour, so that the passage through the colon without obstruction becomes possible.

Another measure that often cannot be avoided in colon surgery is the installation of an artificial anus (anus praeter), which may result in strong mental distress for the patient. The artificial anus serves the purpose of running off stool and gas of a section of the colon through the abdominal wall to the outside and into a bag. If part of the small bowel is substituted, one calls it ileostoma, if it is part of the large bowel its name is colostomy. The stoma can be installed as a short-term measure with the intention to restore the continuity of the colon by retranslocation after some months, or as permanent measure. The reasons for the installation of a stoma are different:

1. threatening intestinal obstruction due to a tumour that cannot be removed;

2. inflammatory diseases in the colon;

3. to protect a diseased section of the colon, until it is again fully functional.

If the surgeon has to place a stoma, he will prepare a sufficiently big opening in the abdominal wall in a suitable place. The stump of the colon is cautiously pulled out through it and then carefully sutured. The opening of the colon lies now in the abdominal wall and is provided with a special bag. Many patients feel very troubled by the installation of a stoma. They feel that they are not socially acceptable any more, and they are ashamed even if today's one-way material for the maintenance of the stoma is excellent and conveys a feeling of security to the patient. Sometimes, a self-help group of people with a stoma (ILCO) can help, which assists patients in many respects. Moreover, there are specialists in care, so-called stoma therapists, who are of help to patients.

[1] http://www.ilco.ch/

What happens after the treatment?

As a rule, the patient is nursed at the intensive care unit for 1 - 2 days after the operation. All important laboratory factors are controlled, and a sufficient analgesic and infusion therapy is administered. The patient continues to take in antibiotics. Due to the intestinal anastomosis, the patient is not allowed to eat and drink for up to 5 days to avoid leakages in the area, a complication which is very difficult to be treated. After these days, the patient is allowed to drink a little, so that the bowel can take up its activity again. This might be quite a painful time for the patient because the bowel will be partly overinflated (paralysis, see above) and take up its activity often accompanied by convulsions. Slowly, the natural nutrition process is started again, beginning with soups and mashed food. For patients with extensive tumours, an additional chemotherapy or radiotherapy, in consultation with the oncologist, may be carried out. If the patient received a stoma, a special stoma therapist would acquaint him with the procedures and materials which are part of the stoma care. Depending on the size and nature of the removed tumour, an individual after-care is carried out. At defined intervals, the tumour markers will be controlled, and an ultrasound, a CT examination of the abdomen, and possibly an enteroscopy might be carried out. This is to make sure that neither metastases nor a new tumour have developed.

History

Still 150 years ago, about two thirds of the patients with intestinal hernia operation died. Even after smaller interventions like the amputation of toes or fingers, 10% of the patients died. The reasons for this high mortality were lacking anaesthesia, antisepsis, and the shock problem. Shock can be caused by severe loss of blood or bacteria that seeped in and may result in death. But then, pioneering discoveries were made, constituting the firm foundation for every great abdominal surgery. Horace Wells realized the first narcosis in 1844 using laughing gas, and in 1901, Karl Landsteiner discovered the blood groups of the human being. This furnished the possibility to perform blood transfusions during great surgical operations and to successfully treat the blood-loss shock. However, the greatest achievement was the finding of Ignatz Philipp Semmelweiss that the wound infections at that time were mostly fatal, especially the childbed fever, because of lacking hygiene of hands and instruments. Until then, an intensive disinfection of the hands was entirely unknown in hospitals. Without knowing it, one carried the bacteria from one patient to another. Unfortunately, Semmelweiss was too progressive for his time, so that his appeals for a disinfection of the hands with carbolic acid, even if proved effective, were at first not taken seriously by many doctors, among them the famous discoverer of the bacteria, Luis Pasteur. It was the surgeon Joseph Lister in Glasgow, who had heard of Semmelweiss' ideas and used them with success in his hospital in 1867. The hands of the surgeons were washed with soap containing carbolic acid before the operations, and a carbolic solution was sprayed over the area of surgery during the operation. This reduced the number of fatal complications after operations considerably. Because of these findings, operation theatres were built that could only be entered with mouth guard and head bandage. This was the reason why the first great and aseptically carried out abdominal surgeries were much more successful from 1880 onwards. An example for the sense of a new era in abdominal surgery, due to the new conditions mentioned, is the work of the surgeon Ulrich Kroenlein, who worked and taught at the University Hospital at Z?h since 1881. He put the new sanitary ideas into action in his hospital by having the floors tiled, by removing bedsteads made of wood, and by building a new surgery for instruction in the form of an amphitheatre. As one of the first surgeons, Kroenlein operated cases of acute appendicitis and worked on the therapy to fight purulent peritonitis, which occurred after injuries of the bowels. In order to avoid peritonitis that occurred because of bad sutures of the bowel (anastomosis), two other famous surgeons of that time made an effort to develop new suturing techniques in abdominal surgery: Theodor Kocher and Vinzenz Czerny. Theodor Kocher writes in 1894: "The intestinal resection has become an extraordinarily important and comparatively frequent surgical intervention, by which the surgeon can save many lives otherwise being considered lost if he carries it out correctly." At the same time, he introduced his running perineal suture. This is why Sir Ernest Miles was able to carry out the first radical abdominoperineal resection of a rectum carcinoma, a very great intervention, in which the colon and the rectum are completely removed.

 

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