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Colon Cancer


OVERVIEW OF Colon Cancer :

Colonal cancer is the malignant transformation of the colon  of the cancer.


STRUCTURE of Colon Cancer :

The colon is the part of the large intestine. It includes ascending colon, descending colon, transverse colon, caecum.

Ascending colon:

It is the starting point of the large intestine. Undigested foods are absorbed here.

The main function of the ascending colon is to reabsorb water and nutrients from the waste materials

Transverse colon:

It transfers the food from one side to the opposite side.

Descending colon:

It is present in the left side of the pelvic region just beneath the diaphragm.

Sigmoid colon:

The sigmoid colon is ‘S’ shaped organ

The sigmoid colon is the last part of the large intestine and it is present between the rectum and colon.

The ileocaecal valve paves the connection between the small intestine and the colon. And it also demarcates the caecum from the colon.


EPIDEMIOLOGY :

the peak incidence appears in the 5th decade of the life and it is the third most common cancer in men.


CAUSES :

 

.pylori infection

Food habits- food rich in fat and oil

Age

Polyps-benign growth seen at the inner surface of the colon

Familial history/ genetics

Inflammatory bowel disease- ulcerative colitis and crohns disease

Chronic exposure to radiation

Smoking

Alcohol consumption

Ingestion of higher amount of NSAIDs

 

 


PATHOPHYSIOLOGY :

The genetic and other triggering factors leads to the activation of the oncogenes and inactivation of the tumour suppressor genes.

Inactivation of the DNA repair mechanisms


COMMON CLINICAL SIGNS AND SYMPTOMS :

  • rectal bleeding or blood in the stool,
  • dark-colored stool,
  • change in bowel habits,
  • change in stool consistency,
  • constipation,
  • diarrhea,
  • narrow stools
  • weight loss
  • iron deficiency anaemia



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DIAGNOSTIC :

Colonoscopy:

The patient is sedated and physician looks for an abnormality in the intestine with a computer aided device.

Biopsy:

It is the removal of a small amppount of tissue for examination under the microscope. A biopsy is the confirmatory test for colonal cancer or colonal cancer.

Biomarketing testing of the tumour:

The colonal cancer should be tested for problems in mismatch repair proteins called mismatch repair defect.

Blood test:

Patient with the colonal cancer may tends to bleed through rectum. This results in the aneamia in patients. Complete blood count might reveal whether the bleeding is occurring or not.

Other levels of protein such as the carcinoembryonic antigen which detects if the cancer has spread to other regions or not.

Fecal immunochemical test:(FIT0

This test reveals if the blood is present in the stool or not

Guaiac based feacl occult blood test(gFOBT):

It is similar to the FIT but it reveals the occult blood in stool.

Fecal DNA test:

It tests the genetic mutations and presence of cancer cells in the stool.

Computed tomography:

A CT scan takes three dimensional pictures of the abnormal tissues from different angles.

Magnetic Resonance Imaging:

A MRI scan uses the combination of the magnetic and radiowave frequency to view the abnormal tissues.

An dye is injected in the vein or the patient is asked to swallow the dye and the results are observed.

Ultrasound:

A sound waves to create the picture of the internal organs to find out if the cancer is spread or not.

Chest x ray:

The chest x ray might reveals whether the cancer has spread to the lungs or not

Positron emission tomography (PET) or PET-CT scan.:

A PET scan is a way to create pictures of organs and tissues inside the body. A small amount of a radioactive sugar substance is injected into the patient’s body. This sugar substance is taken up by cells that use the most energy. Because cancer tends to use energy actively, it absorbs more of the radioactive substance. However, the amount of radiation in the substance is too low to be harmful. A scanner then detects this substance to produce images of the inside of the body.

  • Stages:
  • Stage 0:
  • The cancer is not spread but has potential development of the cancer in the future which is termed as carcinoma insitu.
  • Stage 1:
  • The cancer cells are consider to the localized area. This is also called the early stage cancer
  • Stage 2 and Stage 3:
  • It indicates that the cancer cell has spread to the nearby lymphnodes or tissues.
  • Type 4 :
  • It indicates that the cancer has spread to other parts of the body and also it easily gets metastasis. This is also called an advanced type of cancer.
  • Another common staging tool is the TNM system, which stands for Tumor, Node, Metastasis. When a patient’s cancer is staged with TNM, a number will follow each letter. This number signifies the extent of the disease in each category. According to the National Cancer Institute and MD Anderson experts, the standard TNM system uses the following rules:

    Primary tumor (T)

  • TX: Main tumor cannot be measured.
  • T0: Main tumor cannot be found.
  • T(is), or T in situ: The tumor is still within the confines of the normal glands and cannot metastasize.
  • T1, T2, T3, T4: Refers to the size and/or extent of the main tumor. The higher the number after the T, the larger the tumor or the more it has grown into nearby tissues. T's may be further divided to provide more detail, such as T3a and T3b.
  • Regional lymph nodes (N)

    Lymphatic fluid transports immune system cells throughout the body. Lymph nodes are small bean-shaped structures that help move this fluid. Cancer often first spreads to and through nearby lymph nodes.

  • NX: Cancer in nearby lymph nodes cannot be measured.
  • N0: There is no cancer in nearby lymph nodes.
  • N1, N2, N3: Refers to the number and location of lymph nodes that contain cancer. The higher the number after the N, the more lymph nodes that contain cancer.
  • Distant metastasis (M)

    Metastasis is the spread of cancer to other parts of the body.

  • MX: Metastasis cannot be measured.
  • M0: Cancer has not spread to other parts of the body.
  • M1: Cancer has spread to other parts of the body.

 


TREATMENT AND PROGNOSIS :

Surgery:

Laproscopic surgery:

With this technique several scopes are placed inside the colon when patient is under anesthesia.  Anesthesia is medicine that blocks the awareness of pain. The incisions are smaller and the recovery time is often shorter than with standard colon surgery. Laparoscopic surgery is as effective as conventional colon surgery in removing the cancer. Surgeons who perform laparoscopic surgery have been specially trained in that technique.

  • Colostomy for rectal cancer. Less often, a person with rectal cancer may need to have a colostomy. This is a surgical opening, or stoma, through which the colon is connected to the abdominal surface to provide a pathway for waste to exit the body. This waste is collected in a pouch worn by the patient. Sometimes, the colostomy is only temporary to allow the rectum to heal, but it may be permanent. With modern surgical techniques and the use of radiation therapy and chemotherapy before surgery when needed, most people who receive treatment for rectal cancer do not need a permanent colostomy.

Radiofrequency ablation:

Using an computer aided device the physician passes the needle which emits the electric current in the tumour and causes the tumour to shrink or ablation.

Cryoablation:

  • A cryoprobe containing liquid nitrogen is placed onto the liver tumours and the it results in destruction of the tumour

 

Chemotherapy:

 

A chemotherapy is after the sugery or before the surgery to shrink the cancer cells. A chemotherapy is nothing but the delivery of drug intravenously.

The following are the certain type of drugs which are used in the chemotherapy:

 It includes:

    • C

Radiation therapy:

It uses powerful x rays or emission of protons to destroy the cells. The radiation therapy also aids  in shrinkage of the cells and also relief the symptoms caused by the cancer.

Immunotherapy

it is a drug treatment that uses your immune system to fight cancer. Your body's disease-fighting immune system may not attack your cancer because the cancer cells produce proteins that blind the immune system cells from recognizing the cancer cells. This immunotherapy boos those cells and helps the body to fight against it.

Targeted therapy:

This therapy involves targeting the specific organs. It involves the emission of rays.


PROGNOSIS :

The 5 year survival rate of the colonal cancer is 80%.


PREVENTION :

Intake of fiber foods

Avoid smoking

Avoid alcohol consumption

Increases the physical activity- aids in digestion process

Drink lots of water

Eat well cooked foods


Medicines used in the Treatment :

         

  • Capecitabine (Xeloda), a pill that is changed into 5-FU once it gets to the tumor.
  • Irinotecan (Camptosar)
  • Oxaliplatin (Eloxatin)
  • Trifluridine and tipiracil (Lonsurf)
  • paclitaxel
  • cisplantin
  • 5-fluorouracil


REFERENCE :

https://www.cancer.net/cancer-types/colonal-cancer/diagnosis

https://www.cancer.org/cancer/colon-rectal-cancer/treating/chemotherapy.html

https://www.cancer.gov/about-cancer/treatment/drugs/colorecta

https://www.cancer.org/cancer/colon-rectal-cancer/detection-diagnosis-staging/survival-rates.html

https://www.healthline.com/health/colonal-cancer/prognosis-and-life-expectancy