Incidence and Etiology of Cancer – Introduction to the Biology of Cancer #3
This video is part of an online course, Introduction to the Biology of Cancer by Johns Hopkins University. The course introduces the molecular biology of cancer …
Hello and welcome to the Johns
Hopkins School of Medicine course
on the Introduction to Cancer Biology.
My name is Ken Pienta and
I'm a professor or Urology,
Oncology, and Pharmacology at
the Johns Hopkins School of Medicine.
And I've been a cancer researcher and
physician for over 25 years.
We put this course together
because cancer is one of the most
devastating diseases that strikes men,
boys and girls in the US and
as we will show you worldwide.
It is a disease that is increasing,
it is a disease that's increasing in
incidents as well as every year
it kills more and more people.
We hate cancer, we want to find ways
to find cancer and treat cancer.
We are hoping that this introduction
will give you a sense of the problem.
Not only how it affects people and
their families, but
the biology of how it starts, and
what many of the questions are in
learning how to try to understand cancer
better, and to treat cancer better.
So we are offering this course as
a way to attract you to the field.
To understand cancer better, to contribute
to understanding cancer better.
To contributing to diagnosing it.
To contributing to treating it.
To hopefully finding a cure someday for
this devastating disease.
This first lecture is going to be on
the Incidence and Etiology of Cancer.
At the end of this module you
will be able to define cancer,
understand where cancer starts, identify
the most common types of cancer and
identify the risk factors for
the common types of cancer.
The lecture outline we're going to go
through the cancer terms and definitions,
the incidence in men and women,
globally in the US of cancer overall,
and then we're going to talk about
the six most common cancers worldwide,
lung cancer, colon cancer,
breast cancer, prostate cancer, and
stomach, and liver cancer.
Let's start with cancer terms and
What is cancer?
In it's simplest form,
it means uncontrolled growth.
It's the disease caused by
an uncontrolled division
of abnormal cells in the part of the body.
It's often also referred to as a tumor.
Tumor is defined as a swelling of
a part of the body, generally without
inflammation, caused by an abnormal growth
of tissue whether benign of malignant.
Cancer is also sometimes
referred to as a neoplasm.
Which is defined as a new and abnormal
growth of tissue in some part of the body.
At its heart, cancer is a genetic disease.
It is caused by an accumulation of
detrimental variations in the genome over
the course of a lifetime.
These are a lot of terms that are new, and
will be described in subsequent lectures.
It's important to remember that most
of the time a single mutation in your
genes is not sufficient to
induce cancer formation.
Where does the word cancer come from?
The origin of the word cancer is
from the Greek karkinos, or crab.
And it was termed this because
the Greek physicians Hippocrates and
Galen, among others,
noted how a cancer looked like a crab as
tumors had swollen veins along the skin.
It then evolved to the Latin term
cancer which also means crab or
later, malignant tumor.
Interestingly enough in the old English,
cancer meant spreading sore or cancer.
The study of cancer is oncology, and
where does the word oncology come from?
It literally means a branch of science
that deals with tumors and cancers.
The word onco means bulk or mass or
tumor, while logy means study.
So it's the study of a bulk or a tumor.
An important word in cancer is metastasis.
Metastasis is the spreading of cancer
from a primary site to distant organs and
it literally comes from the Greek
word metastasis, which is removing,
removal or migration, a changing,
a change, or revolution.
So again the metastasis, which means
the spread of cancer from primary site,
to distant organs is an important to
learn early in the study of cancer.
Where does cancer start?
Cancers are classified according to
the tissue where they originate.
There are four main types.
Carcinomas arise in epithelial tissue
that is found in the internal and
external linings of the body.
Adenocarcinomas, which are the most common
form of cancer develop in an organ or
For example, prostate cancer,
breast cancer, liver cancer.
Squamous cell carcinomas develop in
the squamous epithelium of organs,
including the skin, bladder,
esophagus, and lung.
Sarcomas, which account for
less than 10% of all cancers, arise from
connective tissue that is found in bones,
tendons, cartilage, muscle, and fat.
Leukemias are cancers of the blood
that originate in the bone marrow and
Lymphoma refers to cancers that
develop in the lymph system.
This is a schematic of
what cancer looks like.
In this case, cancer of the cervix.
On the left hand side, you can see
normal cells lining an organ and
you can see that each cell looks the same.
And each nucleus, inside the cell which
contains the DNA, looks the same.
The first step towards
cancer is hyperplasia,
where you get a growth
in the number of cells.
It's a proliferation in
the number of cells, and
they start to look a little bit atypical.
As cancer progresses you get mild
dysplasia where the cells start to bunch
up on each other and they start to have
abnormal nuclei and abnormal shapes.
This gets more severe and you develop
carcinoma in situ or cancer in place.
This is where the cells are growing
in an uncontrolled fashion,
they look abnormal and
their nuclei look abnormal.
When cancer starts to invade in metastasis
that's when we refer to it as a carcinoma.
Let's look at some examples.
Here's a histology slide of
prostrate cancer or a carcinoma.
Prostate cancer is an adenocarcinoma.
Here in the slide you can see large,
normal glands with an epithelia lining.
As you develop low-grade cancer you
see that the glands get smaller and
And then as the cancer gets worse and
on the right hand side you see
lose all the gland architecture.
And you just have bunched up cells.
This is even clearer in
this example of sarcoma.
Which in this particular
case is a Ewing sarcoma.
On the left you see
normal connective tissue,
with lots of space between the cells.
And, on the right, you see how
the cancer is just uncontrolled growth.
A proliferation of cells.
You can see big nuclei there.
Cells that don't look normal.
There's just a huge difference that
is very obvious between the left and
the right hand side of the slides.
Here is leukemia which again starts in the
bone marrow and circulates into the blood.
This is an example of acute
The red blood cells that carry your oxygen
are the small doughnuts that you see
in the background and they're carrying
iron and oxygen to oxygenate your blood.
The leukemia cells are just
a proliferation of what we call blasts,
over growth of cells with big nuclei,
big cytoplasm and
this is what acute lymphoblastic
leukemia looks like.
Again, it's a proliferation
of a certain type of cell that
then takes over the blood in body.
This is an example of
a mantle cell lymphoma.
Again, all you see in this picture
is an over-growth of cells
that are out of shape.
They're different shapes and
And the lymph node, the normal lymph
node is totally effaced in this picture.
It is nothing but cancer cells.
And they start in the lymph node so
they are called lymphoma.
This ends our section on cancer terms and
definitions where we
explained what cancer is,
where it starts, and gave you some
examples of what cancer looks like as
it starts in those various organs.
We are now going to move on and talk about
the instance of some of these cancers.