What causes the DNA damage? Normal cells grow, divide in a normal pattern, then die and new cells are replaced. The life cycle of normal cells are under control. Once there is a defect in this life
cycle, the cells will divide in a faster rate than usual due to the loss of the normal body control upon them; those abnormal cells are named cancerous cells. The
most common cause of damaging cells are by accident during the normal cell cycle. Environmental factors such as cigarette smoking and alcohol consumption
have a great influence. Unfortunately, no exact reason is known for cancer yet!
Spread of cancerous cells Cancerous cells have the ability to invade other tissues. When they invade the blood or the lymphs, they will spread all around the body to grow elsewhere in the
body forming new tumors, this process is known medically as “Metastasis”.
Different types of cancer Wherever the cancerous cells spread, it’s named as the first place it started. For instance, if breast cancer spreads to liver, it is named medically “metastatic
breast cancer”, not “liver cancer”! Each type of cancer behaves in its own way, thus the treatment of cancer depends on different factors mainly type of it.
Not all tumors are cancer! The term “Tumor” is quite different from the term “Cancer”. Actually cancer is a type of tumors, while not all tumors are cancer! Tumor is a term used to describe
as abnormal growth of cells. However, tumor cells either may have the ability to invade other tissues which is called “Cancer”, or they are not able to invade other
tissues in which it is called “Benign Tumors”. Benign tumors are never life threatening because they can’t metastasize to other parts of body.
Cancer Society of America | Understanding Cancer | Cause, Symptoms & Risk Factors of Cancer | Cancer Diagnosis | Cancer Prevention, Early Detection & Treatment
Spread of Cancerous cell Cancerous cells have the ability to invade other tissues. Malignant tumor, unlike benign tumor, effects and destroys nearby organ(s).
Eventually, cancer cells eventually break off through blood or lymphatic system to produce new tumors in other parts of body. This
process of spreading called medically "metastasis". Metastasis may last anywhere as short as a few weeks to as long as several
years. Leaving the cancer cells untreated, they eventually invade and spread and destroy the original organ that has effected as well as
those they spread and metastasised.
At the molecular level, how cancerous cells start to divide? When abnormal cells start to divide out of control, the cancer starts. Those cancerous cells will not die, instead they will resume
dividing and growing until they start to invade other tissues. These two characteristics must be in any cell to name it a cancerous cell:
1) out of control cell growth and division, 2) the ability to invade other normal tissues. Basically the defect is in the DNA of the cells.
As we know the DNA is the guide of cellular life cycle. In normal cells, if the DNA gets damaged for any reason, the cell will try to fix
itself, if it fails to do that, it will start a process of killing itself. However, in cancerous cells, the cell neither can repair the damaged
DNA, nor it dies by itself!
Cancer is not just one disease, there are more than 200 types of cancers which can
occur at any part of the body! Our bodies consist of trillions of cells. All parts of body
including blood, bones, organs, muscles, tissues and skins are composed of cells.
Normal cells constantly are reproducing by dividing and multiplying to replace old
damaged cells. Normal cells grow and die and are replaced by new cells in an orderly
fashion. When these orderly reproduction of cells get out of control, and reproduce
themselves in an abnormal fashion, excess cells are formed to be known as tumor. In
most of the cases, these tumors are not life threatening; they are called "Benign
Tumors", not cancer. But once these cells begin to divide and multiply, they become
cancer cells forming "Malignant Tumors".