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Colorectal Cancer

Colorectal Cancer

Overview

Colorectal cancer is a type of cancer that develops in the colon or the rectum. These types of cancer belong in the same group because they share some features in common. They are the result of cells growing out of control, able to spread to other parts of the body. Colorectal cancer usually starts as a polyp. A polyp is a growth that may develop in the inner lining of the colon or the rectum. Although many polyps are benign, some can become malignant. The two main types of polyps are the following:

  • Adenomatous polyps. Adenomatous polyps are more likely to become cancerous and lead to cancer.
  • Hyperplastic and inflammatory polyps. These kinds of polyps are more common and less likely to become malignant and lead to cancer.

Polyps characteristics that increase the risk of colorectal cancer

  • The polyp is more than 1 cm.
  • You have more than two polyps.
  • You removed your polyp, and doctors found dysplasia on it.

How common is colorectal cancer?

There will be an estimated 104,610 new cases of colon cancer, and about 43,340 new cases of rectal cancer in 2020 in the US. Colorectal cancer is the third most common type of malignancy in both sexes, excluding skin cancer. One in every twenty-three men and one in every twenty-five women will develop colorectal cancer at least once in their lifetime. Finally, colorectal cancer will kill an estimated 53,200 people in 2020 in the US. However, screening and advancing therapeutic methods led to a drop in the overall death rate of colorectal cancer.

Risk factors for colorectal cancer

For colorectal cancer, there are some risk factors you can modify or change, and some you cannot. The following are most of the risk factors for colorectal cancer that you can change:

  • Being overweight or obese
  • Being physically inactive
  • Eating lots of animal protein, such as red meats and dietary products
  • Smoking tobacco
  • Drinking excessive amounts of alcohol

The following are some of the risk factors for colorectal cancer that you cannot change:

  • Being older, especially more than 50 years old
  • Having a family history for colorectal cancer or adenomatous polyps
  • Having a personal history of colorectal cancer, polyps, or inflammatory bowel disease
  • Having an inherited syndrome, such as Lynch syndrome or familial adenomatous polyposis
  • Being an African American or a Jew of Eastern European descent
  • Having diabetes mellitus type 2

Causes of colorectal cancer

Doctors do not know what exactly causes colorectal cancer. However, they suggest that risk factors play a vital role in cancer formation. Scientists believe that colorectal cancer is the result of inherited or acquired genes mutations or changes that modify how some cells behave, divide, and grow. Some inherited gene mutations lead to medical conditions, such as Lynch syndrome, familial adenomatous polyposis, Peutz-Jeghers syndrome, or MYH-associated polyposis (MAP).

Symptoms and signs of colorectal cancer

Sometimes, symptoms and signs of colon and rectal cancer overlap due to their similar presentation. Others are asymptomatic early in the course of the disease. Screening is an essential intervention that may reveal early colorectal cancer, even in the absence of symptoms. The following are some of the most common symptoms and signs of colon and rectal cancer.

Symptoms of colon cancer

  • A change in your bowel habits that is persistent, alternating between diarrhea and constipation
  • A change in the consistency of your stool
  • Rectal bleeding
  • Blood in the stool
  • Abdominal pain or cramps
  • Abdominal discomfort, such as gas
  • A feeling that you need to empty your bowel
  • Fatigue and weight loss

Symptoms of rectal cancer

  • A change in your bowel habits that is persistent, alternating between diarrhea and constipation
  • A change in the consistency of your stool
  • Blood in the stool that is red or darker
  • Mucous in the stool
  • Abdominal pain and discomfort
  • Anemia
  • Narrow stool
  • A feeling that you need to empty your bowel
  • Fatigue and weight loss

Diagnosis of colorectal cancer

Diagnosing and staging colorectal cancer is a lengthy procedure. Your doctor will start by taking your medical history and performing a clinical exam, which might include abdominal palpation and digital rectal examination (DRE). During DRE, your doctor will insert a lubricated, gloved finger inside your rectum to check for any growths. Also, if you complained of blood in the stool, your doctor might recommend a stool test to check for blood in the stool that is invisible to the human eye. Other tests you might need to diagnose and stage colorectal cancer are the following:

  • Blood exam, to check for anemia, liver enzymes, and tumor markers
  • Diagnostic colonoscopy, with which your doctor will visualize your entire colon
  • Proctoscopy, if your doctor suspects rectal cancer
  • Biopsy, to confirm the malignancy and establish the type of colorectal cancer, depending on the cancerous cells
  • Imaging tests, to see if cancer spread

Adenocarcinoma, the most common type of colorectal cancer

In about 96% of all cases of colorectal cancer, the type of tumor is an adenocarcinoma. Other less common types of colorectal cancer are carcinoid tumors, lymphomas, sarcomas, and gastrointestinal stromal tumors.

What is the treatment of colorectal cancer?

We could divide colorectal cancer treatment into local and systemic therapies. Your doctor will decide what the best option is for you, depending on the type of cancer, its stage, your age, and your overall health. Local treatments might include surgery to remove the tumor, ablation and embolization, and radiation therapy. Systemic treatments might involve chemotherapy, targeted therapy, and immunotherapy. Depending on the factors already mentioned, you might need monotherapy or a combination of some therapeutic methods, applied simultaneously or the one after the other.

References
https://www.cancer.org/cancer/colon-rectal-cancer/about/key-statistics.html
https://www.mayoclinic.org/diseases-conditions/colon-cancer/symptoms-causes/syc-20353669
https://www.mayoclinic.org/diseases-conditions/rectal-cancer/symptoms-causes/syc-20352884

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