Understanding Cancer – What is Cancer?

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Human body is a complicated and amazing structure of bones, flesh, veins and a trillion of small and tiny living cells. Cells are what make up the human body and work in an orderly fashion. Normal cells start to grow and then later split into new cells. The new ones keep multiplying and the old ones keep dying.

Cancer

Cancer is the dreaded term given to a situation when cells in any part of the human body start to grow abnormally. Cancer can be of many different types, all beginning with an uncontrollable growth of abnormal cells in the body. A cancer cell is different from a normal cell. A cancer cell, unlike the normal cell, doesn’t die. It keeps growing and form new yet abnormal cancerous cells.

There are six main characteristics of cancer that have been proposed [1]. These characteristics are:

  1. Growth of cancerous cells is self sufficient: normal cells need external factors and signals for growth. The signals are carried and transmitted through the receptors which pass through cell membrane. In a normal cell when these signals are absent and aren’t given, growth of more cells stops. A cancerous cell on the other hand, doesn’t need signals to grow. They grow without any external growth signals. Some cancer cells can even produce their own signals.
  1. There is insensitivity in the anti growth signals of cancerous cells: the growth of a normal cell is kept under control. The growth inhibitors that surround the environment on the surfaces of neighboring cells keep it under control. Cancer cells however, resist these signals from their neighbors that prevent growth.
  2. The avoidance of apoptosis. Apoptosis is defined as the process of cell death that is programmed. In this natural mechanism, the cells are programmed to die in a situation where it becomes damaged. The cancer cells are able to get through this mechanism. Cancer cells must always overcome apoptosis in order to further develop.
  3. The replicative potential is limitless: a normal healthy cell will die after it has been divided a certain number of times. On the other hand, a cancerous cell tends to go beyond this limit and is instead capable of growing and increasing indefinitely. These cells are cancerous and harmful in nature as they have damaged chromosomes.
  1. Sustained angiogenesis: Angiogenesis is defined as the process in which previous and existing blood vessels end up forming new blood vessels. To ensure a constant supply of nutrients and oxygen in the cells, cancer cells kick start the process. Initially, cancer cells tend to lack the ability of angiogenesis process. Their ability to expand is limited. They need development of blood supply in order for further progress. Inhibitors and inducers balance the process of angiogenesis.
  2. Activating metastasis along with tissues invasions. Metastasis is a process in which cancer cells start to spread from one part of the human body to other parts and infecting them too. Cancerous cells tend to break away from the organ’s origin in order to spread to other parts of the body and invade tissues of surrounding areas.

Besides these, four new hallmarks were proposed. These were:

  1. Deregulated metabolism: cancerous cells tend to use unusual metabolic pathways in order to generate energy.
  2. Evading immune system: the cancer cells don’t appear to be visible to the body’s immune system.
  3. Instability of the DNA: cancer cells usually have severely damaged and abnormal chromosomes. These abnormalities tend to get worse as the disease progresses over time.
  4. Inflammation: many types of cancer can be induced through chronic inflammation.

Cancer is still a complicated disease. It varies widely. Despite the tones of research and development that has been done towards the disease, a lot still remains to be discovered. There are still many factors to be uncovered and unfolded that would make the disease less life threatening.

With modern science and medical developments, there has been significant progress in treatments for patients who are infected with this unfortunate disease. However, diagnosis of cancer and treatments of the disease still needs a lot of further development and progress as people losing their lives because of this disease is still very high.

Causes of Cancer

Cells become cancer cells because of damage to a person’s DNA [2].  DNA controls the actions of a cell and is present in all the cells. When damaged in a normal cell, DNA repairs itself or kills the cell. In a cancer cell however, DNA doesn’t get repaired or die. Instead, it keeps on producing newer cells all of which include the damaged DNA.

Difference between cancer cell and a normal cell

Cancer cells differ from normal cells in several ways which lets them become uncontrollable and invasive [3]. Cancer cells tend to be less specialized than normal cells. Cancer cells continue to grow and divide without a stopping limit. Normal cells have specific functions while cancer cells do not. Cancer cells aren’t programmed to stop dividing and die after a limit unlike normal cells which stop dividing. Cancer cells don’t get the signals that make them stop dividing. It is possible for cancerous cells to effect normal cells as well. They can affect and influence the blood vessels and the molecules surrounding the tumor.

Cancer cells are deadly and powerful and can mess up the entire system of the human body. Unlike normal cells, cancer cells are able to evade the body’s immune system as well. The immune system is basically a network that functions by protecting the human body from different types of infections and various other kinds of medical conditions. This network is made up of organs, tissues and the specialized cells which help in the functioning of immune system. Even though the immune system is powerful and is usually able to free the body from damaged cells by removing abnormal cells from the body, some cancer cells still manage to escape the protection of the immune system. Immune system can also be used by tumors in order to stay alive and grow further.

Types of Tumors

Under most situations, the cancer cells end up forming tumors. These cancerous tumors are also known as malignant tumor. Cancer cells can spread around the body and infect other parts too. They can replace the tissues and form new tumors. The process is known as metastasis.

However, all tumors are not cancerous. Non cancerous tumors are called benign tumors. Unlike malignant tumors, these tumors are not very life threatening. They don’t spread and infect other parts of the human body.

Malignant Neoplasms

This term is used to refer to growth of tissues in the human body in an abnormal manner. Even the growth is abnormal; it does not usually turn into a mass. That’s the more usual case but in rare cases it does turn into a mass. These cases don’t happen too frequently. As compared to the normal cell, these cells have a nucleus that is bigger in size and also function quite differently than a normal cell. Cells could be of several different types of shapes and sizes. Having an uncontrolled pattern of growth, they often invade tissues. If they interfere with normal functioning of the body, they can become life threatening as well. These cells also sometimes tend to go through metastasis and spread to other parts of the body.

Benign Tumors

Benign tumors unlike malignant tumors are non cancerous. They are not seriously life threatening unless the tumor occurs at some vital body part. These tumors don’t grow too fast and their growth is considerably slow. They don’t spread into the other parts of the body. Their treatments are simpler as well. Once they have been removed through surgery, they are not likely to come back. These kinds of tumors are rarely serious.

Signs and Symptoms of Cancer

When cancer symptoms occur in the body, there are visible changes in the body that should be watched out. The symptoms usually occur at the body part where cancer is most likely to grow. The challenging thing about diagnosing cancer however can be due to the fact that the symptoms are not often too clear to be taken seriously at the most treatable and initial stage. This is because the symptoms are too general and can be easily ignored. Since cancer is not just a single type of disease but is a group of diseases with over a hundred cancer types, signs and symptoms widely differ [4]. This makes it very hard to make a list of definitive symptoms. However, there are a few typical symptoms of cancer which include the following:

  • Occurrence of a lump in any part of the body which doesn’t feel normal
  • A change occurring in any mole of the skin
  • Constant coughing
  • Hoarseness of voice
  • Changes in usual bowel movement in the form of constipation or diarrhea
  • Difficulty in digesting food
  • Difficulty in swallowing food
  • Difficulty in passing urine
  • Sore or ulcer that is persistent and wouldn’t go
  • Unusual bleeding from the vagina
  • Unusual blood in stool or urine
  • Sudden and unexplained weight loss
  • Pain in the abdomen
  • Sweating at night due to any apparent and explainable reasons
  • Feelings of fatigue and tiredness without any apparent cause
  • Pain experienced in the body. The pain could occur in bones usually at the backbone or the hipbone.
  • Rashes in skin or changes in skin texture
  • Loss of appetite. The sufferer doesn’t feel the hunger and urge to eat meals.
  • Rust colored phlegm or spit
  • Shortness of breath
  • Loss of appetite
  • Dizziness and headaches

Most of the symptoms and conditions that have been mentioned above are very general in nature. They can occur for many conditions other than cancer too. This is what makes diagnosing cancer so challenging. It is important to always see the doctor as soon as any unusual health conditions are experienced. Significant or not, the doctor will treat them right away.

Drivers of Cancer

There are three main drivers of cancer. The genetic changes which lead to contributions in cancer mainly affect three types of genes. These genes are proto-oncogene’s, tumor suppressor genes and DNA repair genes [3].

The first type of genes; proto-oncogene’s are basically involved in growth of cells and division of cells. When these genes allow the cells to grow when they shouldn’t and let them strive and thrive, these become cancer causing genes.

The second type of genes; tumor suppressors have the function of controlling growth and division of cells. The cells in tumor suppressor genes may divide uncontrollably.

A DNA repair gene which is the third type of genes or the third type of cancer driver is involved in fixing of DNA that has been damaged. Some cells in these genes have mutations which tend to eventually develop additional mutations in other genes as well. When these mutations come together, they may often end up causing the normal healthy cells to become cancerous.

As has been mentioned above, the spread of cancer is done through a process called metastasis. The metastasis cancer cells and original cancer cells look the same under a microscope. These cancer cells usually have the same molecules. The chromosome change in both types of cells is similar. Metastasis cancer can cause very severe damage to the bodily functions and is the leading cause of deaths in cancer patients. There are treatments that could help in increasing life span of people who have metastasis cancer. They have the main goal of controlling the process of metastasis and control the growth of cancer cells in the body.

Cancer is a deadly and dreaded disease which could often be life threatening if it’s not diagnosed within time. Understanding cancer and how it works has been a complicated task for the scientists always and still continues to be.

 

References


[1] Hanahan, Douglas;Weinberg, Robert A. (January 7, 2000). “The hallmarks of cancer cell” http://en.wikipedia.org/wiki/The_Hallmarks_of_Cancer


[2] http://www.cancer.org/acs/groups/cid/documents/webcontent/003115-pdf.pdf


[3] http://www.cancer.gov/cancertopics/what-is-cancer


[4] Possible symptoms of cancer. Cancer Research UK. Retrieved 07 December 2013 http://cancerhelp.cancerresearchuk.org/about-cancer/causes-symptoms/possible-symptoms-of-cancer

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