2.- What does colorectal cancer consist of?

It consists on the uncontrolled growth of malignant cells located in the colon and rectum, provoking a tumor that provokes bleeding, obstruction, and perforates the intestine if it is not treated.

In the colon and rectum we can find benign and malignant tumors. The only way to know what type of tumor we are facing is analyzing it with a biopsy (performed with a colonoscopy).

Benign tumors (benign polyps) must be removed as well because they sometimes are the forerunners of cancers. Their removal ensures the recovery of the patient.

Malignant tumors can be removed generally with surgery (both open or laparoscopic), but if this is not done on time, they can invade other tissues and nearby organs, deteriorating the prognosis.

When the colorectal cancer is disseminated (when it expands) out of the colon or the rectum, the tumor cells frequently appear in the nearby lymph glands. If the tumor cells have reached these glands, they may possibly have extended to other lymph nodes, the liver, or other organs.

When cancer is disseminated (a process called "metastasis") from its original location to other parts of the body, the new tumor has the same type of abnormal cells and the same name as the primary tumor. For example, if the colorectal cancer disseminates to the liver, the tumor cells in the liver are in fact tumor cells from the colon or the rectum. The illness is a metastatic colorectal cancer, not liver cancer. The treatment applied is therefore the colorectal type, not the one for liver cancer. Doctors may call this new tumor "distant injury" or metastatic illness.

3.- Who is in risk of suffering from colorectal cancer?

The exact causes for colorectal cancer are not known. Doctors can rarely explain why colorectal cancer affects some people but not others. However, it is clear that colorectal cancer is not contagious. No one can "get" this illness from someone else.

Some people may have some risk factors. We call a risk factor something that can increase the chances of suffering an illness.

The scientific studies have determined the following risk factors for colorectal cancer:

• Age: colorectal cancer is more likely to appear with age. Over 90% of the people with this illness were diagnosed when they were over 50 years old. The average age for this diagnosis is 65.

• Colorectal polyps: polyps are tumors located in the inner wall of the colon or the rectum. They are common in people over 50 years old. Most polyps are benign (not cancerous), but some of them (called adenomas) can become cancerous and are therefore considered pre-malignant. If these polyps are found and removed, the risk of colorectal cancer can be reduced. Family medical history of colorectal cancer: first-line relatives (parents, siblings or children) of a patient with a history of colorectal cancer are more likely to suffer from this type of cancer, especially if their relative developed it at a young age. If many first-line relatives have a family history of colorectal cancer, the risk is even greater.

• Genetic alterations: the changes in certain genes increase the risk of colorectal cancer.

Hereditary nonpolyposis colorectal cancer (HNPCC): this is the most common type of hereditary colorectal cancer (genetic). It conforms 2% of the total colorectal cancer cases. It is caused by the changes in a gene with HNPCC characteristics. Almost 3 out of 4 patients with an alteration in a HNPCC gene suffer from colorectal cancer, and their average age when this is diagnosed is 44.

Adenomatous familial polyposis, normally known as familial polyposis, is a strange and hereditary illness in which hundreds of polyps are formed in the colon and rectum. It is caused by a change in a specific gene called APC. Unless it is an adenomatous familial polyposis, it normally develops into colorectal cancer at the age of 40. Adenomatous familial polyposis is present in less than 1% of all colorectal cancer cases.

These two alterations are susceptible to the study of the Genetic service.

• Personal history of colorectal cancer

The patient who has suffered from this cancer in the past can develop colorectal cancer a second time. Moreover, women with a history of ovarian, uterus, or breast cancer are more likely to suffer from colorectal cancer.

• Inflammatory disease such as ulcerative colitis or Crohn’s disease

Patients which have suffered illness provoking the inflammation of the colon (ulcerative colitis or Crohn's disease) for a long time, have more risks of developing colorectal cancer.

• Diet

The studies suggest that high-fat diets (especially animal fat) and low in calcium and fiber can increase the risk of colorectal cancer. Also, some studies point out that people who barely eat fruits or vegetables are more likely to develop this cancer. More investigations are needed to understand better in which way diet can affect the risk of colorectal cancer.

• Smoking

People who smoke cigarettes are more likely to develop this cancer as well.

4.- How can colorectal cancer be detected?

People with a higher risk of suffering colorectal cancer, as well as those with digestive symptoms (diarrhea, constipation, blood in the faeces, chronic abdominal pain, weight loss, nausea, vomits, etc.) must go under early detection tests such as the faecal occult blood test, colonoscopy, or oncogene marker in blood. Previously, they must proceed with a broad rectal examination.

Diagnostic tests:

Most of the colon illnesses are diagnosed with colonoscopy and/or opaque enema.

- Colonoscopy consists of introducing a flexible tube through the anus, with a diameter similar to a finger that contains a camera. Thus, the endoscopist can see the interior of the colon and even take samples (biopsy) if needed.

- The opaque enema is a special radiologic test in which a liquid contrast is introduced through the anus in order to fill the colon and draw its outline in radiography.

- Nowadays, abdominal computed tomographies (scanners) are extremely important, and doctors can also perform virtual colonoscopies without introducing any camera through the anus. - An abdominal ecography can be useful as an urgent test if the anus, for any reason, cannot be prepared.

The colonoscopy, the opaque enema, and the computed tomography require cleaning the colon with special solutions.

Before the intervention, the corresponding preoperative tests are performed depending on the patient: analysis, radiography, electrocardiogram, anestesiology, etc...

The stages of colorectal cancer are:

• Stage 0: the cancer is located only in the most internal covering of the colon or rectum. It is also called carcinoma "in situ".

• Stage I: the cancer has grown inside the interior wall of the colon or rectum. The tumor has not reached the exterior wall of the colon or has not extended outside the colon. "Duke's A" is another name to this stage I colorectal cancer.

• Stage II: the tumor is extended deeper inside the wall of the colon or the rectum, or through it. It has probably invaded nearby tissues, but the tumor cells have not disseminated to the lymph nodes. "Duke's B" is another name to this stage II colorectal cancer.

• Stage III: cancer has disseminated to nearby lymph nodes, but not to other parts of the body. "Duke's C" is another name to this stage III colorectal cancer.

• Stage IV: the cancer has extended to other parts of the body such as the liver or the lungs. "Duke's D" is another name to this stage IV colorectal cancer.

Relapsing or recurrent cancer: the cancer has been treated but has come back after a period of time in which it was not detected. The illness can go back to the colon or the rectum, or to any other part of the body.

5.- Treatment for colorectal cancer

The treatment for colorectal cancer can include surgery, chemotherapy, radiotherapy, or a combination of all three. Colon cancer is sometimes treated differently than rectum cancer, especially at the beginning of the treatment because many studies point out that rectum cancer is first treated with chemotherapy and radiotherapy, and there are even intraoperative radiotherapy protocols. The most important factor is treating all patients following specific protocols for each stage of the illness.

A.- SURGERY (Colon surgery - figure 1)

It is the main and most common treatment. It consists of removing the polyps, and even the segment of the colon or rectum involved in the tumor if necessary.

Depending on the location of the tumor, the affected blood and lymphatic drainage area of the colon can be removed as well. Thus, in a descendent colon cancer, the left part of the colon is removed. In an ascending colon cancer, the right colon is removed, and so on.

Rectum cancer surgery tries to preserve the anal sphincters in order to avoid the "feared" pouch in the abdomen, used to expel the faeces. However, keeping these sphincters is sometimes impossible, and the anus must be removed to avoid cancerous recurrence). Consequently a colostomy pouch must be applied to the abdominal wall.

Sometimes it is necessary to proceed with a colostomy pouch in emergency interventions: intestinal obstruction and perforation are the most common. In contrast with those cancers in which the sphincters must be removed, these types of colostomies are temporary, and after a few months, a reconstruction can be done so that the patients can expel their faeces through their natural anus.

Nowadays, most colon and rectum surgical procedures can be performed laparoscopically, and therefore recuperation is more comfortable for the patient.

B.-Chemotherapy

Chemotherapy uses anticancer medication to destroy the tumor cells. This is called systemic therapy because it enters the bloodstream and can affect the cancerous cells all over the body.

The patient can receive chemotherapy alone or combined with surgery, radiotherapy or both. Chemotherapy applied before the surgical process is called neoadjuvant therapy. If chemotherapy is applied before surgery, it can "shrink" a big tumor.

Chemotherapy that is applied after the surgical process is called adjuvant therapy. Adjuvant therapy tries to destroy any remaining cancerous cell and thus avoid its recurrence or return to the colon, rectum, or any other organ.

Chemotherapy is also used to treat people in a late stage of the illness.

Anticancer medication is normally administered intravenously, although it can also be done orally. The patient can receive this treatment in the out-patient section of the Hospital, in the doctor's office or at home. In very few

occasions, it can be necessary to stay at hospital during the chemotherapy treatment.

C.-Radiotherapy

Radiotherapy is a local therapy that uses high-energy rays to destroy cancerous cells. It affects the tumor cells only in the area where it is applied.

Doctors use two different types of radiotherapy to treat cancer, and some patients can even receive both:

- External radiotherapy: the radiation comes from a device. Most patients go to hospital or to a clinic to receive this treatment, normally 5 days a week during several weeks. In certain cases, an external radiation is administered during the surgical process. This is known as intraoperative radiotherapy.

- Internal radiation therapy (implant radiation): the radiation comes from a radioactive material inside very slim tubes that are located directly inside the tumor or near it. The patient must remain in hospital, and the implants are left inside for a few days. They are normally removed before the patient goes home.

Treatment for colon cancer

Most patients with colon cancer are treated with surgery, and some can even receive both surgery and chemotherapy. Sometimes it is necessary to perform a colostomy to patients with colon cancer.

Even though radiotherapy is not normally used in this type of cancer, it is sometimes applied to relieve pain and other symptoms.

Treatment for rectum cancer

In all stages of this cancer, surgery is the most common procedure. Some patients receive surgery, radiotherapy, and chemotherapy. Almost 1 out of 8 patients with rectum cancer needs a permanent colostomy.

Radiotherapy can be applied before or after surgery. Some people receive radiotherapy before the surgical intervention to "shrink" the tumor, and some others receive it afterwards to destroy the tumor cells that may remain in the area. In some hospitals, patients can receive radiotherapy during the surgical intervention (intraoperative radiotherapy). In addition,

patients can also receive radiotherapy to relieve pain and some other problems derived from cancer.