Colorectal-cancer

What is Colorectal Cancer ?

Colorectal cancer occurs when normal cells in your colon or rectum start to grow abnormally. Initially, cancer may start as a polyp, or small growth, in your colon or rectum. The cancer cells can spread to other parts of the body.

This cancer is also called colon cancer or rectal cancer, depending on where cancer has occurred. It is most common in people older who are older than 50.

Symptoms of Colorectal Cancer

Some of the symptoms of colorectal cancer are as follows:

  • Changes in bowel habits
  • Diarrhoea or constipation
  • A feeling that the bowel does not empty properly after a bowel movement
  • Blood in feces
  • Bright red blood coming from the rectum
  • Pain and bloating in the abdomen
  • A feeling of fullness in the abdomen
  • Fatigue or tiredness
  • Unexplained weight loss
  • A lump in the abdomen
  • Unexplained iron deficiency in men, or women after menopause

Causes of Colorectal Cancer

The cause of colorectal cancer isn’t exactly known. But there are some factors or conditions which can lead to the development of cancer, which are:

  • Age (Most common for people older than 50)
  • Race (Mostly found in African-American race)
  • Diet high in fat
  • Polyps in colon
  • Ulcerative Colitis
  • Family history of colon cancer
  • Familial Adenomatous Polyposis (FAP)

Stages of Colorectal Cancer

The most common system used for staging lung cancer is the TNM system.

T stands for Tumour. It is used to describe the size of the tumour. It also helps to determine whether the tumour has grown into other parts of the organ or tissues around the organ. It is represented by a range of 1 to 4. The higher the number means the larger the tumour.

N stands for Lymph Nodes. It helps determine if cancer has spread to the lymph nodes around the organ. NX means the impact on lymph nodes cannot be determined. N0 means cancer hasn’t spread to nearby lymph nodes while N1, N2, and N3 means cancer has spread to lymph nodes. N1 to N3 also shows the range that how many lymph nodes are affected.

M stands for Metastasis. It is used to determine if cancer has spread to other parts of the body through blood or lymphatic system. MX means the metastasis cannot be determined; M0 means cancer has not spread to other body parts while M1 indicates that it has spread to other body parts.

Sometimes lowercase letters like a, b and c are used to divide the tumour, lymph nodes, and metastasis into subcategories. Also lowercase “is” is used to denote carcinoma in situ. E.g. Tis

For the convenience of grading the extent of spread of cancer, the cancer is classified into 5 broad stages.

Stage 0

It is the earliest stage of cancer. In this stage, cancer is present only in the innermost lining of the colon. It has not spread anywhere. This stage is also known as carcinoma in situ.

Stage I

In this stage, cancer has spread to the middle layers of the lining of the colon. It has not spread to any lymph nodes or any distant sites. This stage is also referred to as Dukes’ A colon cancer.

Stage II

Stage II consists of sub-stages based on the spread of cancer. This stage is also called Dukes’ B colon cancer. It is divided into three groups

Stage IIA: In this stage, cancer has grown into the outermost layers of the colon or rectum but has not gone through them. It still has not spread to the lymph nodes or distant sites.

Stage IIB: Cancer has grown through the wall of the colon or rectum but has not grown into nearby organs. It has not spread to nearby lymph nodes or distant sites.

Stage IIC: Cancer has spread outside your colon to nearby tissues or organs. It has still not spread to the lymph nodes or distant sites.

Stage III

This is one of the advanced stages of cancer. It has the following characteristics:

Stage IIIA: Cancer has spread to the middle layers of the colon wall and also has spread to one to three lymph nodes. It hasn’t spread to any distant sites

Stage IIIB: Cancer has grown into middle layers or outer areas of the colon or rectum and has spread to four to six nearby lymph nodes. It hasn’t spread to any distant sites.

Stage IIIC: In this stage, cancer has grown into or through the outer layers of the colon or rectum but hasn’t reached nearby organs. It has spread to seven or more nearby lymph nodes, but not to any distant sites.

Stage IV

It is the most advanced form of cancer. In this stage, cancer may or may not have grown through the wall of the colon or rectum, and it may or may not have reached any nearby lymph nodes. It has spread to one distant organ (such as the lungs or liver) or one of the distant set of lymph nodes.

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Colorectal Cancer

Risk Factors

Certain factors increase the chances of developing colorectal cancer. These are as follows

Age
Infection by HPV
Diet high in fat
Polyps in colon
Family history of colon cancer
Familial Adenomatous Polyposis
Adenomatous polyps
Inflammatory bowel disease (IBD)

Types of Colorectal Cancer

There are various types of cancers of colon and rectum. They are as follows:

  • Colorectal adenocarcinoma: Adenocarcinomas of the colon or rectum mostly develop in the lining of the large intestine. They start in the inner lining and then spread to other nearby layers.
  • Gastrointestinal carcinoid tumors:Carcinoid tumors occur in nerve cells called neuroendocrine cells, whose function is to help regulate hormone production. These are slow-growing tumors
  • Primary colorectal lymphomas: This type of cancer occurs in the lymphocytes which are a type of cell that helps the body in fighting against infections. It accounts for about 1 percent of all colorectal cancers.
  • Leiomyosarcomas: It is a cancer of the smooth muscle of colon and rectum, this occurs very rarely.

Diagnosis of Colorectal Cancer

There are many ways in which colorectal cancer can be diagnosed; the following are some of the most recommended diagnostic techniques:

  • Colonoscopy: Colonoscopy allows the doctor to see directly inside the colon. If a doctor finds any polyps or tissue during the examination it will be removed and collected for
  • CT Scan: Colon and rectum cancer can be detected by CT scan of the respective organs.
  • Stool DNA Test: This test analyses several DNA markers that colon cancers or precancerous polyps cells shed in the stool
  • Imaging test: This test will help in knowing the area where cancer has spread.

Treatment of Colorectal Cancer

The following treatment systems can be implemented for colorectal cancer :

  • Surgical removal of the affected part of colon and rectum
  • Radiation therapy to kill cancer cells in the affected area.
  • Chemotherapy to kill or restrict the growth of cancer cells in colon and rectum.
  • Immunotherapy is designed to boost the body’s natural defences to fight against the cancer. It uses materials made either by the body or prepared in a laboratory to improve, target, or restore normal immune system function.
  • Targeted Therapy: It blocks the growth and spread of cancer cells while limiting damage to healthy cells by targeting specific protein or gene.

Prevention of Colorectal Cancer

A number of lifestyle measures can help in reducing the risk of developing colorectal cancer:

  • Diet rich in fruits and vegetables can help preventing cancer
  • Moderate exercise is great for starting your day
  • Regular screening for cancer can help you determine the extent of cancer.