Module 3: Applications of BiologyTopic: Social & Preventative Medicine (Cancer)Institution: Montego Bay Community CollegeLecturer: Mrs. S. Desouza

Information Compilers:

Hariel Walker

Joelle-Ann Griffiths

Tiann Peterkin

Editors:

Le-Jay K. Robinson

Daena Ruddock

Power pointer: Le-Jay K. Robinson

To discuss the reason for regional distribution of cancer and this will be done by:

Outlining the role of environmental hazards, food additives, viruses and genetic factors.

Implications of symptom awareness and failure to seek treatment in management of the disease

A disease caused by an uncontrolled division of abnormal cells in a part of the body. [1 mark]

Cancer refers to any one of a large number of diseases characterized by the development of abnormal cells that divide uncontrollably and have the ability to infiltrate and destroy normal body tissue. [2 mark]

Brain Tumor

Eye Cancer

Nasal Cavity Cancer

Esophagus Cancer

Lung Cancer

Breast Cancer

Stomach Cancer

Cervical Cancer

Prostate Cancer

Stomach Cancer

Lung Cancer

Colorectal Cancer

Formation

Cancers are a result of uncontrolled cell division. The type of nuclear division involved is mitosis. The problem is caused by mutations or abnormal activation of the genes which control the division. When the genes are abnormal they are called oncogenes. A single faulty cell may divide to form a clone of identical cells. Eventually an irregular mass of relatively undifferentiated cells called a tumor is formed. Tumor cells can break away and spread to other parts of the body, particularly in the bloodstream or lymphatic system, causing secondary tumors or metastases. This process is called metastasis.

Causes of

Cancer

Retroviruses are RNA viruses which, when they invade animal cells, use the enzyme reverse transcriptase to make DNA copies of the viral RNA. The DNA is inserted into the host DNA where it may stay and be replicated for generations of cells.

An example of this is the human immunodeficiency virus (HIV), which contains a gene that alters host cells, switching them on and causing them to become malignant. The genes become oncogenes.

DNA viruses contain DNA as their hereditary material. Some contain there own oncogenes which can cause uncontrolled cell division of host cells.

An example of this is papilloma viruses which causes warts.

About 5% of human cancers show a strong genetic predisposition, in other words they tend to run in families. More than 40 types of cancer including breast, ovary and colon cancer come into this category.

The genes responsible may be oncogenes, or genes which lead to failure to kill cancer cells.

This includes X-rays, ɣ-rays and particles from the decay of radioactive elements. The radiation causes the formation of chemically active and damaging ions inside cells which can break DNA strands or cause mutations.

This is the most common form of carcinogenic radiation and is non-ionising. DNA absorbs UV-light and the energy is used in converting the bases into more reactive forms which react with surrounding molecules.

However Prolonged exposure can result in melanoma which is highly malignant.

Radon gas is a natural source of radiation released from certain rocks such as granite. It may accumulate in houses in areas where these rocks are found. Exposure to this radiation has been linked to the development of leukemia, lung, kidney and prostate cancers.

Many chemicals are now considered as carcinogenic. The first example was described in 1775 as soot and coal tar, when chimney sweeps were discovered to develop scrotum cancer. Tobacco smoke contains chemicals responsible for lung cancer, the most important of these are polycyclic hydrocarbons which are converted in the body to carcinogens.

Symptoms

A symptom is a signal that’s felt or noticed by the person who has it, but may not be easily seen by anyone else. For example, weakness, aching, and feeling short of breath may be symptoms of pneumonia.

Cancer is a group of diseases that can cause almost any sign or symptom. The signs and symptoms will depend on where the cancer is, how big it is, and how much it affects the organs or tissues. If a cancer has spread (metastasized), signs or symptoms may appear in different parts of the body.

A cancer may cause symptoms like fever, extreme tiredness (fatigue), or weight loss. This may be because cancer cells use up much of the body’s energy supply, or they may release substances that change the way the body makes energy from food. Cancer can also cause the immune system to react in ways that produce these signs and symptoms.

Surgery: can be used to diagnose, treat, or even help prevent cancer in some cases. Most people with cancer will have some type of surgery. It often offers the greatest chance for cure, especially if the cancer has not spread to other parts of the body.

Chemotherapy: is the use of medicines or drugs to treat cancer.

Radiation Therapy: uses high-energy particles or waves to destroy or damage cancer cells. It is one of the most common treatments for cancer, either by itself or along with other forms of treatment.

Targeted Therapy: is a newer type of cancer treatment that uses drugs or other substances to more precisely identify and attack cancer cells, usually while doing little damage to normal cells.

Immunotherapy: is treatment that uses your body's own immune system to help fight cancer.

Photodynamic therapy: is a treatment that uses special drugs, called photosensitizing agents, along with light to kill cancer cells. The drugs only work after they have been activated or "turned on" by certain kinds of light.

An untreated cancer will continue to grow indefinitely , however not all cancers are the same. Some grow very fast (within 48 hours) and some grow very slow (up to 30 years). A cancer also has the ability once it reaches a certain point to replicate itself by seeding the body with millions of 'new mutated cancer cells' , this is called metastasis. When a cancer becomes metastatic it will shed 'cancer cells' into the blood stream or lymphatic system and send new cancer colonies anywhere in the body. Those new cells will lodge in the lung, liver, brain, bones, or any other system in the body and grow new cancer tumors which in turn will continue the cycle. Eventually the cancer will consume the entire body and begin to affect the normal functioning of body systems which will lead to organ failure and death. It is possible for the entire body cavity to be filled with tumors, they can also erupt through the skin and spread on the surface as well.