Download 2.- What does colorectal cancer consist of?

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 outpatient 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.