Question

5. Can risk assessment be used for both familial and non familial cases of cancer?

6. What are the tests used for early detection of non familial colon cancer?

7. Is cancer age dependent? Give reasons

Answer 1

5. Ans : Risk assessment of cancer can be done for both familial and non familial cancers.

For familial or genetic cancers, a list of factors like familial history in first and second degree relatives, ethnicity of parents and grandparents etc are assessed for risk. Other factors include gender and current age of the relatives with cancer and the age at diagnosis. A family history of colon cancer doubles a person's risk of developing the disease. Studies have shown that about 5-10% of colon cancers are inherited, risk assessment of familial colon cancer helps to a great extend in early detection and treatment.

For non familial cancers, exposure to carcinogens like tobacco and radiation are taken into consideration. These factors are modifiable through lifestyle changes and are casually related to cancer.

6. Ans : There are several methods used for the early detection of non familial colon cancer.

1. High-sensitivity Fecal Occult Blood Tests (FBOT) : This method detects small amounts of blood in feces that may go unnoticed by the eyes. There are two types of FBOT tests.

• Guaiac FBOT/gFBOT : a chemical is used to detects the presence of heme in stool. Heme is a component of hemoglobin in blood.
• Fecal Immunochemical Test/iFBOT : the hemoglobin protein in blood is detected using an antibody

2. Stool DNA test (FIT-DNA) : Stool of a colon cancer patient contains blood and cells fron the inner lining of colon and rectum. Thia method uses antibodies for hemoglobin as well as 9 different biomarkers of three major genes involved in colon cancer.

3. Sigmoidoscopy : A sigmoidoscope is a minimally invasive device used to view the inner lining of the sigmoid part (lower part) of colon and to collect abnormal growth samples. It is a long tube with a lighted head that contains a camera for viewing and a an instrument to remove tissues for biopsy. The tube may be flexible or rigid. Once it is inserted, air is pumped into the colon to expand it which facilitates better viewing of the lining.

4. Standard or Optical colonoscopy : Colonoscope works similar to sigmoidoscope except that it also allows to examine the upper part of the colon unlike sigmoidoscope.

5. Virtual Colonoscopy/ Computed Tomographic Colonography (CTC) : This method uses a CT scanner that generates a series of pictures of the colon and rectum which are then assembled to form detailed images of any abnormal growth. Hence it is a less invasive method as compared to standard colonoscopy.

6. Double-contrast barium enema : This is another method used to view the lining of colon using a series of X-ray images taken from outside the body after giving the patient an enema with barium solution which helps to outline the colon and rectum in the images. Although this is a non invasive method, it is not preferred as it is not as sensitive as colonoscopy.

7. Ans : Cancer is age dependent. Increasing age is the most important risk factor for cancer. People aged around 55 and above have the highest parcentage of cancer cases. As age increases there is higher rate of oxidative stress and mutations that render cancerous properties to cells. Tissues and organs of an aged person provides a microenvironment that enables conversion of normal cells into cancer cells due to various factors like incresed inflammation rate that results in more reactive free radicals that challenge the integrity of cellular components, less efficient DNA repair mechanism and weakening of the immune system which favors the cancer cells to go undetected. The exact reason for the relationship between increased age and higher risk for cancer is yet to be worked out.