Understanding Colon Cancer: Symptoms, Causes, and Treatment Options

Understanding Colon Cancer: Symptoms, Causes, and Treatment Options

Malignant intestinal tumours occupy an inglorious top position in industrialized countries: they are the third most common type of cancer in both men and women. In 2018, 1.8 million people worldwide were diagnosed with colorectal cancer. Almost all malignant neoplasms originate from the glandular tissue of the large intestine mucosa (adenocarcinoma); cancer in the area of ​​the small intestine is sporadic.

Where exactly does the cancer arise?

By far, the most common form of colon cancer is colorectal carcinoma. This means that the tumour is in the area of ​​the colon (colon carcinoma), i.e. a part of the large intestine between the rectum and appendix and the area of ​​the rectum  (rectal carcinoma).

Since the large intestine includes not only the large intestine but also the appendix with its appendix, and the rectum (rectum) up to the anus is an independent section behind the large intestine, the standard terms colon cancer or colon cancer are imprecise.


Causes of colon cancer

Most carcinomas arise from benign mucosal proliferations (adenomas, polyps ). The probability of degeneration depends on the histological structure and the size (from one centimetre) of the soft growth.

Due to increasing mutations, the cells differ so much from the original structure that they develop unregulated and uncontrolled growth. They lose contact with other intestinal cells, leave the cell structure and penetrate the surrounding tissue. If they enter the blood or lymphatic system, they can spread throughout the body and form metastases. Most often, degenerated tissue develops in the rectum. The further up the colon you go, the less common it is.

In the further course of the disease, offshoots can develop, especially in the liver. If the carcinoma is located deep (in the lower rectum), it can also develop in the lungs. From these organs, further spread can take place throughout the organism. People who have a genetic predisposition to develop colon polyps are particularly at risk of developing colon cancer. There are certain genetic diseases (familial adenomatous polyposis = FAP) which, if left untreated, always lead to colon cancer.

In addition, cigarette smoking – as with almost all types of cancer – also promotes malignant growth here. Certain operations in the large intestine (for example, connecting the ureter to the large intestine) or chronic inflammation of the digestive organs ( ulcerative colitis ) are also associated with an increased risk of cancer.

Diet-related influences

Diet-related influences are also known: high-meat and high-fat, low-fiber diets and being overweight are major risk factors. They cause the stool to remain in the intestine longer, and the contact time with the mucous membrane is longer. This irritates the intestinal mucosa, which means that more toxins get into the intestinal cells – and thus increases the likelihood that these will multiply uncontrollably.


Colon Cancer Symptoms

Colon cancer often causes no or, at most, mild and uncharacteristic symptoms for a long time. This is precisely why people over the age of 45 should pay particular attention to the following signs that require clarification:

  • any change in bowel habits (frequent bowel movements at unusual times, persistent diarrhoea and constipation )
  • Abdominal cramps and painful bowel movements
  • Gas, frequent nausea, or unusual feelings of fullness
  • Blood or mucus in the stool (also known as haemorrhoids ), skinny stools due to narrowing of the bowel, extremely foul-smelling stool

Many of these symptoms, such as diarrhoea or constipation, can have very different causes and do not have to be a sign of colon cancer. If in doubt, however, a doctor should always be consulted, especially if the symptoms persist over a more extended period or are recurring.

Blood in the stool should also be checked out by a doctor, even if the person concerned suffers from haemorrhoids – these are so common that cancer and haemorrhoids can occur at the same time. Any cause of blood in the stool must be thoroughly investigated to rule out a possible cancer.

Examination for colon cancer

If there is a suspicion of colon cancer, the family doctor is the right contact person. If necessary, the patient can be referred to a gastroenterologist. After a conversation about the medical history, the doctor can also carry out an occult blood (hemoccult) test. For this purpose, a stool sample is examined in the laboratory for tiny amounts of blood. If the test is positive, this does not necessarily indicate colon cancer. Other diseases, such as haemorrhoids, can also cause blood in the stool.

blood test can also provide initial clues. Depending on the stage of the disease, some patients have a tumour-derived protein  (tumour marker )  in their blood called a carcinoembryonic antigen (CEA). Although this is not suitable for recognizing colon cancer, since it does not only occur in this type of cancer, its determination can be used in follow-up care (if the concentration rises again, this is one sign that the cancer is [again] active ).

In most cases, colorectal cancer is detected by palpating the rectum and by examining the large intestine ( colonoscopy ). To get an impression of the histological type and the degree of degeneration (dysplasia), the doctor simultaneously takes a tissue sample (biopsy). If a colonoscopy does not provide the desired information, an X-ray examination with a contrast medium is available.

With the help of ultrasound, X-ray examinations and computer tomography, the extent of the cancer and the presence of metastases are recorded.

Stages and chances of recovery in colorectal cancer

It is essential for the prognosis of how far the cancer has penetrated the intestinal wall at the time of diagnosis and where it is growing. The closer it sits to the anus, the worse the prognosis since, from there, it can spread its secondary tumours more easily via the lymphatic and blood vessels.

The chances of recovery are excellent if the malignant tumour cells are limited to the intestines. Even if the intestinal wall is exceeded and the lymph nodes are affected, more than half of the patients can still be cured. However, if there are multiple liver metastases, the probability of survival is (still) low; if there is only a single metastasis, there is hope for a cure.

The earlier a finding (polyp or cancer) is detected, the smaller the intervention and the better the prognosis. The therapy aims to cure the affected person of his cancer (curative treatment). Age and general condition, as well as the extent of the tumour, are necessary influencing factors.

In general, there are five stages of colorectal cancer:

  • Stage 0:  In this earliest stage, it is usually determined after removing a polyp during a colonoscopy that cancer cells were already present in its mucous membrane. Further therapy is generally not necessary here.
  • Stage I: A small early-stage tumour is also usually discovered during a colonoscopy and removed in a minor surgical procedure using an endoscope. At this stage, colorectal cancer is easily curable.
  • Stage II: Surgery to remove the tumour is usually necessary. In the case of colon cancer, this usually ends the treatment, while additional radiation and chemotherapy are often carried out in the case of rectal cancer.
  • Stage III: In this stage, the colon cancer has already spread to the lymph nodes. In addition to surgery, chemotherapy and radiation therapy are required.
  • Stage IV: The tumour has already metastasized to other organs. These are treated with medication and surgery.


Complications of colon cancer

Particularly in the case of very fast-growing tumours, there is a risk of intestinal obstruction ( ileus ), which must be surgically repaired immediately. Metastases can prevent the outflow of bile and lead to liver failure.

Colon cancer surgery

The heart of the treatment of colorectal cancer is still the surgical procedure. The surgeon tries to preserve the anal sphincter when removing the affected section of the colon to maintain regular bowel movements. But this is not always possible, especially if the cancer is in the lower part of the intestine or has already spread widely. Then, the end of the bowel is passed out through the abdominal wall via an artificial bowel outlet (colostomy). The metastases (mainly in the liver) are also surgically removed if possible.

In recent years, overheating (hyperthermia) by microwaves or the introduction of chemical agents directly into the metastasis have been added as further therapy options. The combination of surgery and subsequent chemotherapy and radiation can improve the prognosis. In the future, a cure will be possible even with extensive disease findings.

Palliative Therapie

If an operation is not an option, an attempt is made to alleviate the symptoms (palliative therapy). This is done by maintaining intestinal patency (narrow points can be irradiated with a laser if necessary) and through the use of chemotherapy and X-rays.


Proper nutrition for prevention

Various substances in food are said to have an intestinal protective function, such as vitamins ( vitamin E, C, folic acid ) and acetylsalicylic acid. However, the studies yield contradictory results – in some cases, even more cases of cancer were observed with high-dose vitamins. Instead of taking food supplements, it makes more sense to eat a varied and balanced diet: low in fat, high in carbohydrates and fibre, lots of vegetables and fruit, and lots of liquid, ideally green tea. This guarantees a sufficient supply of vitamins without the risk of overdosing and a fast passage through the stool, thanks to plenty of dietary fibre.

Exercise should also prevent obesity – at least it supports intestinal activity and helps fight it.

Cancer screening and colonoscopy

Many experts recommend colonoscopy at regular intervals (every three years) from the age of 50 as part of early detection in addition to the annual rectal examination. Routine stool examination for blood should also be part of the cancer screening. 

Successfully treated patients must undergo a precisely specified tumour follow-up, which consists, among other things, of proof of the CEA. With these measures, a recurrence (recurrence) of the cancer can be detected and treated early.

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