This flow chart. Do not let it intimidate you. Do
not let it overwhelm you. That is not the point.
The point of this is, I am going to show you, step
by step how you are going to take every one of
this boxes and apply it to what you need
to know for carcinogenesis.
Once we have discussed the entire flow chart,
you will come back and take a look at it
and my goodness you will tell yourself
this is really simple. It is.
Everything that you need to know about
carcinogenesis is in this flow chart.
I will take each one of this boxes and I will spend prudent
time so that you are able to effectively learn,
what then caused mutation to the normal cell.
Take a look at the top of this flow chart.
You have the normal cell. And the normal cell got
exposed to whatever type of carcinogen.
And as the mutation continues eventually, take a look now.
You are going to move from the normal cell,
and as you go through every box or we shall be
going through every box. At some point in time,
you have so much malignancy with increased nuclear
to cytoplasmic ratio, that there is every
possibility that the cancer may then rupture
through the membrane and result in?
Take a look at the bottom portion of this flow chart
and over to your right you will notice that now
the malignant cell has ruptured through
the membrane resulting in metastasis.
Our job and objective is to make sure that we go
through the entire flowchart from top to bottom.
Take in the boxes that we see in the side
and I will show you how to utilize,
how a chemical mutation genetically, what
have you, may result in a cancer.
Our first order of business will be the box on
your left. I will walk you through chemicals
that are responsible for developing cancer.
Radiation and viruses. And once we are done,
I will keep coming back to this flowchart in which
you will see exactly as to where you are located.
Let's begin. The chemicals. Where we are on that
flowchart, over to your left is that box.
Important chemicals that you would want to know for
your boards responsible for developing cancer.
Now before we begin, there is something called
a Ames test. It screens for carcinogens.
It detects mutagenic effects on bacterial cell in
culture. Assumes that mutagenicity in vitro,
in the lab correlates with the carcinogenicity
in-vivo, your body. This is called a Ames test.
If i were you, I would know at least the definition
of Ames test. Screening for carcinogens.
Our first chemical is one in which let's
say that you smoke your meat.
An entire population that does this quite
commonly would be out in the far east.
You are thinking about Japan and perhaps China. To the
point where the government itself has got involved
and wishes to educate it's society so that it tells
them to not smoke their meat and so therefore
not consume nitrosamine is my topic. And the reason
for that is, consumption of nitrosamine,
via smoking your meat then results in developing
a type of gastric adenocarcinoma.
In the United States, it's incidence is dropping
becaause, well, we don't smoke our meats as much
and we have done a good job in terms of educating our
society with consumption of nitrosamines.
First chemical here that we are looking at that
may result in a type of cancer. Know it well.
Asbestos. With asbestos, this is a topic
that we cover in pulmonology
especially when we start talking about
asbestos in development of lung cancer.
That's your first order of business. Now with
asbestos, who is your patient?
Well all that stuff we will talk about later. With asbestos, it
will come specifically under Restrictive Lung Disease in Pulmonology.
Restrictive Lung Disease. And under restrictive lung
disease, we will talk about a topic called pneumoconiosis.
Are you with me? And if you are confused, that's okay because in
pulmonology we will be spending quite a bit of time with pneumoconiosis.
Asbestos. Your patient might have been working in a
naval shipyard. Or maybe your patient was a roofer.
And with exposure to asbestos, with different types
of fibres that the patient is breathing in.
One is called chrysotile, and by chrysotile it means
that it's a serpentine or the curved like fiber,
which is quite common. Not as carcinogenic as the
other type of fibre and it's known as your,
well, it's dangerous. It's straight and brittle. And that
type of asbestos fiber when breathed in or inhaled,
may then result in a bronchogenic carcinoma. The only
cause in United States of mesothelioma is asbestos.
Now, those patients that are watching commercials, and
on your commercials there is mesothelioma, always comes on.
And therefore patient would think the most common type of
lung cancer that asbestos causes is mesothelioma.
That could not be further from the truth. The most common
type of lung cancer that one would develop after exposure
to asbestos especially the amphibole particle. The
amphibole would be the straight and brittle.
This is much more carcinogenic. Would be bronchogenic carcinoma.
We'll talk about this later but this is a chemical.
Also perhaps renal cell carcinoma but the big one
that you are paying attention to will be lung.
Nitrosamines, asbestos. Other chemicals that you need
to know that may result in cancer include
chromium and nickel. What might you be doing here,
in which the patient develops lung cancer? Mining.
Okay? Mining. Arsenic? mining as well. Now,
when you say mining, be careful,
because you might be mining for coal and that is completely
different. Here you're mining for, well, different metals.
And when you are mining you might then be exposed to
different chemicals. So, maybe it's chromium and nickel,
maybe it's arsenic. Now, when you hear arsenic, by reflex
you should be thinking about apart from the skin,
you should also be thinking about the liver. Two
major organs here. Arsenic, upon exposure,
squamous cell cancer of the lung, squamous cell
cancer of the skin. And in the liver,
a condition known as angiosarcoma of the liver.
Angiosarcoma could take place in a number of organs
but most likely you should be thinking about the liver.
Chromium and nickel, arsenic. Topic, chemicals
that give rise to cancer. Other chemicals that you must
know that are responsible for developing cancer,
vinyl chloride. What industry is your patient working
in and what is your patient being exposed to,
to develop angiosarcoma of the liver with vinyl chloride.
Plastic. Vinyl chloride, a chemical that might be,
or is considered to be carcinogenic. Now this one is interesting.
It's unfortunate. Your patient comes in with a cancer,
and indications show that chemotherapy must be started. And
the particular chemotherapeutic agent that you choose to
administer your patient will be an alkylating agent. Unfortunately
while treating your patient for cancer with alkylating agent,
your patient develops a secondary cancer. Unfortunate.
It might be either leukaemia or lymphoma.
That is how to interpret alkylating agent. Napthylamine.
Napthylamine could be found with perhaps cigarette.
And with cigarettes though there is other chemicals
including aromatic amines, hydrocarbons are big ones.
And when you are smoking, the type of cancers
that you may develop include in the lung,
small cell lung cancer and squamous cell lung cancer.
Both of those. Lung, also urinary bladder.
So with smoking you might then develop transitional cell cancer
of the urinary bladder. We'll talk further about that later.