Colorectal cancer

colorectal cancer summary

Colorectal cancer is a malignant disease that affects the large intestine and rectum. It is one of the most incident types of cancer in the world, being responsible for several deaths. In Brazil, according to INCA, almost 30,000 people were affected with colorectal cancer in 2010, it is the fourth most common cancer in Brazil. The South and Southeast regions are the ones with the highest incidence of the disease, with Rio Grande do Sul and Rio de Janeiro being the states with the highest incidence of the disease.
Its causes are not yet fully understood, however some factors may increase the risk of developing the disease, such as a family history of colorectal cancer and eating habits. The disease is usually more common after the age of 50. People who are overweight, sedentary and with inflammatory diseases in the large intestine are some of the risk groups for the disease.

Symptoms are characterized by changes in bowel habits with abdominal pain, blood in the stool, gas, sudden weight loss, among others. Diagnosis is usually made by colonoscopy and biopsy. Complications of the disease include metastasis (spread of cancer to other parts of the body) and complications from surgery to remove the tumor, such as infections and bleeding.

Treatment depends on how advanced the tumor is. The main therapies are surgery, radiotherapy and chemotherapy (including so-called smart treatments or targeted therapy). Immunotherapy, alone or in combination with another treatment, is sometimes used against metastatic colorectal cancer1.

It is important to emphasize that colorectal cancer, when diagnosed early, has a high chance of cure and patient survival. Therefore, if you are over 50, get checked regularly. Also be aware if you have cancer in your family. Some prevention tips are: weight control, changes in eating habits, moderate alcohol consumption and smoking cessation.


Colon and rectum cancer or colorectal cancer is a malignant disease that is characterized by tumors that reach the colon (large intestine) and rectum (last portion of the large intestine). Often, the tumors developed are benign, not characterizing a cancer, called adenomatous polyps. However, some of these polyps can become malignant tumors.

The most common type of colorectal cancer is colorectal adenocarcinoma, which originates from the glands present in the colon and accounts for more than 90% of cases. Other types lymphomas (originating from the lymph nodes of the large intestine) and squamous cell carcinoma (of epithelial origin).


– Colorectal cancer is one of the most incidents in the world, especially in developed countries, being the third most common type of cancer in both sexes.

– North Americans are particularly affected by this type of cancer, probably because of the high rate of obesity and bad eating habits, such as eating a lot of hamburgers, soft drinks, etc. In the United States, a country with more than 300 million people, about 100,000 cases of colorectal cancer are registered per year and about 50,000 deaths. There are slightly more men who die from this type of cancer than women.

– In Europe, it is the most common cancer. There are approximately 430,000 new cases each year and over 200,000 deaths. According to a press release from the United European Gastroenterology (UEG) published in October 2017, colorectal cancer leads to around 215,000 deaths each year in Europe. According to this release, research recently revealed that 3 out of 10
colorectal cancer diagnoses involve people under 55 years of age.


The causes of colorectal cancer are still not fully understood. Some factors identified as possible triggering causes of colorectal cancer are:

– Eating habits: diets high in fat and red meat may be linked to the causes of cancer.

meat and cancer

On October 26, 2015, the International Agency for Research on Cancer (IARC), linked to the WHO, evaluated the carcinogenicity of consumption of red meat and processed meat.

– The IARC has classified the consumption of red meat as probably carcinogenic to humans. This association (red meat and cancer risk) was observed mainly with regard to colorectal cancer, but other associations were also observed for cancers, such as pancreatic and prostate. Red meat refers to all types of meat from the muscle tissue of mammals, such as beef, veal, pork, lamb, mutton, horse and goat.

– IARC experts have classified processed meat as a human carcinogen based on sufficient evidence that consumption of processed meat causes colorectal cancer in humans.

Processed meat refers to meat that has been processed by salting, aging, fermenting, smoking or any other process used to enhance flavor or improve shelf life. Most processed meats are pork or beef, but processed foods can also contain other red meats, poultry, offal or by-products such as blood.
Read:  Consumption of processed meats increases the risk of colorectal cancer

– Genetic mutations: as with other cancers, genetic mutations in the cells of the large intestine and rectum can lead to the appearance of tumors. Certain mutations can be transmitted hereditarily and account for about 20% of cancer cases. Some of these mutations can also cause some syndromes that are responsible for increasing the risk of developing the disease. People with cases of colorectal cancer in the family are more likely to develop the disease, which is a hereditary cause.

– Familial Adenomatous Polyposis (FAP): it is a rare disease that causes the development of several polyps (mushroom-shaped clusters of precancerous cells) in the colon and rectum. When left untreated, this syndrome increases the chances of developing cancer.

– Hereditary Non-Polypso Colorectal Cancer (HNPCC): also known as Lynch syndrome, this condition increases the chances of developing colorectal cancer, even under 50 years of age.

– Sitting for a long time. An Australian study published in the American Journal of Epidemiology in April 2011 showed that sitting for 10 years doubles the risk of developing colorectal cancer compared to those who are not constantly seated during their workdays.

Colorectal cancer risk groups

The incidences demonstrate that colorectal cancer affects both men and women. Within the general population, some groups at risk for the disease are:

– People over 50 years old, since most cases of colon and rectum cancer are detected in these patients;

– Patients with a family history of colorectal cancer or polyps;

– Patients with hereditary syndromes that increase the incidence of colorectal cancer, such as Familial Adenomatous Polyposis and Hereditary Non-Polypso Colorectal Cancer;

– People with diets low in fiber and high in fat and red meat;

– obese and sedentary;

– Patients with high alcohol consumption;

– Smokers, including passive smokers;

– Patients with inflammatory bowel diseases, such as chronic ulcerative colitis and Crohn’s disease ;

– Patients who have already been exposed to ionizing radiation, such as in radiotherapy.

It is important to emphasize that patients who have one or more risk factors will not necessarily develop cancer. The disease has a complex pathophysiology that depends on both genetic factors and environmental causes. It should also be mentioned that colorectal cancer, when detected early, has a high chance of being cured.


The main symptoms of colorectal cancer mainly affect the lower digestive tract. These signs typically include:

– Changes in bowel habits, such as frequent diarrhea or constipation without any apparent cause.

– Presence of bloody stools (melena).

– Intestinal and anal bleeding.

– Sensation that the intestine has not emptied after a bowel movement, with ineffective effort to eliminate the stool.

– Nausea and vomiting .

– Lower abdominal and anal pain.

– Presence of gases.

– Change in stool consistency.

– Weight loss.

– Anemia (due to blood loss).

– Weakness.

– Tenesmo.

Colorectal cancer, when detected in the early stages, has a high chance of being cured. It’s important to always be alert to these symptoms, especially if you’re part of a risk group. Patients over 50 years of age should talk to their doctor about having a fecal occult blood test. Patients with hereditary conditions or inflammatory diseases (chronic ulcerative colitis etc) should talk to their doctor.


The diagnosis of colorectal cancer is usually made through colonoscopy, an endoscopy aimed at the colon and rectum. When an abnormality is detected, the doctor can use the colonoscopy tube to do a small surgical procedure and remove part of the tissue for analysis (biopsy). The colonoscopy procedure is performed with patient sedation and bowel preparation to receive the tube.

See section: A colonoscopy every 10 years reduces the risk of colorectal cancer by 40%

Differences between men and women regarding colorectal cancer

Among men, tumors are located closer to the rectum, while in women, tumors are located closer to the colon.

Because colonoscopy is more effective in the rectum than in the colon, women are at a higher risk of developing this type of cancer because doctors are less able to reach the colon when performing a colonoscopy. For the French monthly magazine Science &Vie (August 2014 edition), which reported differences between men and women in medicine, physicians should consider this information and improve screening methods in women.

A Canadian study showed in 2010 that colonoscopy in women is less efficient than in men, with a 3-year follow-up after colonoscopy.

Once the disease is detected, imaging tests help detect the extent of the cancer. In this case, CT and X-ray procedures with barium contrast may be necessary. Blood tests are also sometimes needed to analyze cancer markers.

Histological exams determine the stage of the cancer, which can be:

Even after treatment, the cancer can return, which is a case of recurrence of the disease. This can happen in the colon, rectum, or some other part of the body.


Colorectal cancer can proliferate, reaching other parts of the body and generating new cancers in different organs (mainly liver). Another complication is the recurrence of the cancer in the large intestine itself or in the rectum.

Other complications of colorectal cancer can arise from the surgical procedure to remove the tumor. Among them, we can mention: infections, intestinal hernia, hemorrhages, ischemia and necrosis (due to obstruction of arteries and vessels), intestinal perforation, among others.


The treatment chosen for colorectal cancer will depend on the degree of tumor injury and the affected area, in addition to whether or not it has metastasized. The doctor can use 3 main treatment strategies:


When the cancer is small and localized, the doctor may obtain a surgical removal of the tumor mass through the colonoscopy procedure. If the tumor is larger, the doctor may remove it laparoscopically or videolaparoscopy.

If the cancer has grown into the wall of the intestine, the doctor may opt for a colectomy, which is the removal of part of the large intestine or rectum. In this case, the surgeon reconnects the remaining parts of the intestine. However, when this is not possible, the patient will need a temporary or permanent colectomy. For the collection of feces, a special bag is used.

In very advanced cases, the doctor may perform palliative surgery. This procedure is aimed at improving the patient’s symptoms, not completely curing him. Chemotherapy can be used after palliative surgery to improve the patient’s prognosis.


Radiation therapy uses high-energy rays to destroy tumor cells. This procedure can be used to kill remaining tumor cells after surgery, to reduce the number of cells before surgical removal (so they can be removed more easily), or to lessen the symptoms of cancer.

Radiation therapy is more intended for cancers that are advanced and have penetrated deeper into the bowel. To prevent recurrence, radiation therapy is usually combined with chemotherapy.


Chemotherapy is based on administering drugs to kill tumor cells. This procedure can be done before or after surgery, depending on the stage of the tumor. Physicians, before indicating chemotherapy treatment, should test whether the patient has a mutation in the KRAS gene, as it confers resistance to certain drugs.

Examples of drugs used for colorectal cancer chemotherapy are cetuximab, panitumumab, bevacizumab, 5-fluorouracil, oxaliplatin, leucovirine and irinotecan.


Since the 2010s, immunotherapy is sometimes used against metastatic colorectal cancer2 . Immunotherapy called immune checkpoint inhibitors is one of the main immunotherapy used against metastatic colorectal cancer. The immune checkpoint inhibitors used against colorectal cancer are ipilimumab (Yervoy) and nivolumab (Opdivo), they are given by injection (infusion). They are associated with reducing the size of metastatic colorectal cancer with high microsatellite instability (changes in cell DNA) and controlling its growth3.


 Some tips are important in the case of colorectal cancer:

– If you are over 50 years old, have a fecal occult blood test regularly. Early detection of colorectal cancer increases your chances of cure and patient survival. A study published in October 2017, also read in Diagnosis above, recommends starting screening at age 45.

– Always be aware of your bowel habits. If you notice changes without any apparent cause, see a doctor.

– Pay extra attention to symptoms if you have colorectal cancer in your family or have a history of inflammatory bowel disease, such as Crohn’s disease or chronic ulcerative colitis.

– Chemotherapy or radiotherapy treatment can result in several side effects. Talk to your doctor so that he can prescribe a specific medication for nausea , dizziness, vomiting , weakness, anemia , etc.

– If you are diagnosed with the disease, seek support from your friends and family. Don’t take this as a death sentence. Alternatives such as yoga, meditation and physical activities help the patient to live with the disease and have a better quality of life.


Colon and rectum cancer, when diagnosed early, has a high chance of cure. For colorectal cancer prevention patients over 50 years old, it is indicated to do the fecal occult blood test annually. In addition, other tests are indicated such as flexible sigmoidoscopy (every 5 years), double barium contrast enema (every 5 years), colonoscopy (every 10 years), virtual colonoscopy (every 5 years), DNA test in the stool.

Some lifestyle habits can also be adopted to prevent the disease:

– Eat portions of fruits and vegetables, which are rich in dietary fiber and also consume whole grains if possible.

According to a study published in March 2015, in the online version of JAMA Internal Medicine , vegetarians have less risks, about 20% less, of developing colorectal cancer compared to those who consume meat.
Read:  Consumption of processed meats increases the risk of colorectal cancer

– Drink alcohol in moderation.

– Avoid smoking.

– Practice physical exercises.

– Control your weight.

Some preventive measures are indicated for people at high risk of developing colorectal cancer. However, these measures need investigation. Talk to your doctor for more details.

– According to a British study published in 2014, daily intake of 75 to 100 mg of aspirin reduces the risk of bowel cancer by 35% after 10 years of starting treatment, the risk of dying from this type of cancer decreased by 40% . However, the protective effect of aspirin is only manifested during a treatment period of at least 5 years, if possible 10 years. For shorter treatments, the researchers did not see a significant protective effect.

Daily aspirin intake should begin between 50 and 65 years of age, with medical supervision.

Jeanne Kenney
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I’m a stylist trainer, a content creator, and an entrepreneur passion. Virgo sign and Pisces ascendant, I move easily between my dreams, the crazy world I want, and my feet on the ground to carry out my projects.

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