What is cancer?

What is cancer?

cancer cell

When people hear the word cancer, they think of it as

some “thing” in the body: a lump, a mass—the tumor.

Look in a medical textbook, however, and you will find

cancer defined as an abnormal and uncontrolled

growth of cells—a process. To understand how these

two are connected, we first need to understand some

basic biology.

The human body is made up of different parts, called

organs, each performing a particular job that contributes

to the functioning of the body as a whole; for

example, the lungs bring oxygen to our blood and take

away carbon dioxide, while the heart pumps the blood

through the body. These organs, and other kinds of

tissue that make up the parts of the body, are likewise

made up of smaller units, called cells. Normally, cells

divide and mature, performing jobs that are programmed

into their genes, until they age and die, usually

to be replaced by new cells.

A cell turns cancerous when something goes wrong

in this process of cell division. A mutation alters one

or more of a cell’s genes; the cell then starts to divide

more rapidly than is normal, and the resulting cells

fail to develop and perform properly. While normal

cells have as part of their genetic programming

instructions to die and to make way for new cells,

cancer cells do not have this mechanism and continue

to grow unchecked. They accumulate to form a mass,

or tumor, and then invade the normal tissue surrounding

them, impairing or destroying its ability to

function as well. Cancer cells can also spread, or

metastasize, to other organs and areas of the body

where this process of unchecked growth and harm is

repeated.

Metastasis = The spread of cancer from the primary
(original) tumor to another part of the body.

Depending on where it originates, cancer tends to
grow and spread in characteristic ways. On the one
hand, this makes it possible to define specific guidelines
for the diagnosis, cancer staging, and treatment
for each kind of cancer. But because of these differences,
cancer is in reality over 200 different diseases.
Although medical science has grasped the basic biology
underlying cancer as a process, the exact mechanisms
for each type of cancer remain to be worked out.
A number of factors can initiate the process of creating
a malignancy: exposure to chemical and industrial
compounds in the environment; medical drugs, such as
some hormonal and immunosuppressive agents; radiation
exposure; and lifestyle factors, particularly tobacco
and alcohol consumption.

Staging = Systems of classifying a patient’s cancer by
tumor size and how far it has spread in the body.

Malignancy = Tumors that are characterized by the ability to invade
surrounding tissue and spread to other parts of the body.

Carcinogens are those agents that directly cause cells
to grow in an abnormal manner, for example, by altering
a cell’s DNA. There are also cancer promoters and
enhancers that either create conditions that contribute
to cancer development or accelerate the abnormal
growth of cells. Cancer development is a multistage
process, and it takes a number of things to go wrong in
order for the disease to take root and grow. That is
why not everyone who smokes will develop lung cancer,
even though there is no question of the carcinogenic
potential of many of the chemical compounds
contained in tobacco smoke.

DNA = Deoxyribonucleic acid. The molecular
building blocks of chromosomes. They contain and
control genetic information in cells, including how they
divide, grow, and function.

When your loved one is diagnosed with cancer, it is
natural to wonder: Why him or her? Why now?
Because definite answers may not be found, people
often focus on particular things they did, or didn’t do,
or events that may have taken place just prior to diagnosis,
or in the preceding months or years, that were
in reality just coincidental with regard to the cancer.

If you or your loved one thinks that a particular event
or situation caused the cancer, discuss these impressions
with the doctor directly to gain a better understanding
of the possible contributors to the cancer
development and growth.

Misconceptions about cancer often arise when people
generalize or misapply what very well may be true in
limited cases. For example, although there is a virus
associated with the development of cervical cancer, the
cancer itself is not contagious. In fact, there are very
few other cancers that originate in infectious processes.
In a similar vein, although there is a genetic component
to many cancers, there are almost always other
factors involved that result in cancer actually developing;
for this reason, one cannot simply say that cancer
is inherited.