Jack: Hi, all.
In today's lecture, we'll begin discussing lung cancer.
This will be the first in a series of lectures
and in this lecture, we'll cover lung function
and global trends in incidence and mortality.
So the goals of this lecture
are to describe basic lung anatomy and function,
to summarize global lung cancer cases and deaths,
to describe global patterns of lung cancer mortality,
to describe US lung cancer mortality in men and women,
and to describe longitudinal patterns
of lung cancer mortality and cigarette smoking
and the relationship between the two.
So to begin with, this figure from your textbook
presents the anatomy of the human lung.
And human lungs are paired organs
that perform the essential function
of exchanging carbon dioxide in the blood
for oxygen in the air that's breathed in.
The left lung is divided into two lobes,
while the right lobe is divided into three lobes.
And human lungs contain 1500 miles of airways
and 300 to 500 million alveoli,
which are like tiny air sacks
where carbon dioxide is exchanged for oxygen.
And we see a depiction of alveoli
on the right side of the screen here.
Lungs have a large surface area
and a volume between six to four to six liters.
Humans breathe 11,000 liters
containing 2.3 liters of oxygen every day.
The exchange of gases occurs in the respiratory zone,
which consists of respiratory bronchioles, alveolar ducts,
and the alveoli, which, again,
we see in this small right figure here.
There's two different types of cells
in the lining of the alveoli
and this is important because these are the types of cells
that can become cancerous.
So in one year,
over 1.82 million new cases of lung cancer were diagnosed,
and this was 1.24 million in men and 583,000 in women.
This was an overall increase of 13.2% since 2008.
This figure shows that the highest rates of lung cancer
occur in North America, Europe, and China
in this, which is the darker blue color.
And the highest rates of lung cancer
occur in nations with the highest prevalence rates
of chronic smoking, like countries in North America
and Europe, as well as East Asia, like China.
When we look at the depiction
of the mortality rates from lung cancer,
we see a similar pattern.
Lung cancer caused 1.59 million deaths in 2012,
which was more than double that of any other form of cancer.
Nearly 90% of lung cancer patients die from the disease
and most die within a few months of being diagnosed.
In low and middle income countries,
25 to 30% of all cancer deaths are due to lung cancer
and more people die from lung cancer
than breast cancer, prostate cancer,
and colon cancer combined.
Lung cancer was responsible for more than 25 million deaths
in the 20th century,
and it's estimated that 250 million people
will die from lung cancer
and other smoking-related cancers in the 21st century.
In 2020, the updated lung cancer statistics are as follows.
There was a age-standardized incidence rate
of 22.4 per 100,000 people globally.
We see that this is quite a bit more than the rate for women
because men die or are diagnosed with lung cancer
at much higher rates than women are.
For mortality, we see a similar pattern.
Men have a much higher mortality rate
from lung cancer than women do,
with 25.9 out of 100,000 men
dying from lung cancer in 2020.
Globally, tobacco smoke is responsible
for approximately 87% of cases of lung cancer.
The highest rates of lung cancer occur in nations
with the highest prevalence rates of chronic smoking,
as previously discussed,
in North America, Europe, and East Asia,
and lung cancer mortality rates
are the consequence of many years of past smoking exposure.
That's why it's such an issue
that young people throughout the world are taking up smoking
at such high rates.
So up to 50% of the young people
in countries like India, China, and Russia
are picking up the habit of smoking.
This will have devastating health consequences in the future
in the form of lung cancer.
Recent estimates for the 193 member nations
of the World Health Organization
suggests that one in three adults smoke globally.
And we discussed last week
that there's a rising prevalence of chronic smoking
among women, which has made the rates
of female lung cancer incidence and mortality increase.
In the US, cancer of the lung
is the most common cause of cancer-related deaths
among men and women.
The dominant risk factor for lung cancer
is cigarette smoking,
and as we mentioned in a previous lecture,
the early epidemiologic studies
by some British and a United States-based epidemiologist
demonstrated the etiologic link
between cigarette smoking and cancer of the lung.
You'll remember discussing Hill's criteria of causality
and the web of causality.
Cigarette smoking and tobacco use
was really one of the first key linkages
that was elucidated between cancer and a strong risk factor.
Finally, this graph depicts
the increasing odds ratio for lung cancer by amount smoked.
So as we can see on the far right,
men who smoke 41 or more cigarettes per day
have more or have approximately 50 times the chances
of developing lung cancer
or being diagnosed for lung cancer than men who do not.
Similarly, women who smoke 41 or more cigarettes per day
have approximately 30 times the chances
of being diagnosed with lung cancer
than women who do not smoke that many cigarettes per day.
And I will, some of you
may have taken other epidemiology classes before
and be familiar with the idea of an odds ratio.
Essentially, that's showing the likelihood
that one is going to develop a condition
given that they fulfill a certain trait
or characteristic or fit into a specific group.
So in this case,
all the blue bars are showing the odds ratio of women
or the times more likely that a woman
who smokes a certain number of cigarettes per day
is of being diagnosed with lung cancer
than someone who has never smoked a cigarette
or who has smoked zero cigarettes per day.
So this might be a complicated concept
or a confusing concept for some people
that haven't taken an epidemiology
or biostatistic class before.
So if it is, I encourage you to reach out.
I'm more than happy to discuss
some of the epidemiology terms
that might be used in some of the studies
and chapters of your textbook.