Jack: Hi, everyone.
In today's lecture, we'll be discussing cancer prevention.
We have three goals.
We're going to explain the importance
of primary, secondary, and tertiary cancer prevention,
we're going to provide examples
of the three levels of cancer prevention,
and finally, we'll touch upon a summary
of all module one lectures.
So to begin with, primary, secondary,
and tertiary cancer prevention
are the three main categories of cancer prevention.
Primary cancer prevention is avoidance of exposure
to disease-causing risk factors in the first place.
Secondary prevention is screening for the detection
of antecedent conditions that predispose to disease.
When people get screened early
or screened at any point in the disease progress,
they oftentimes have a higher likelihood
of surviving the cancer by being treated early
before the cancer has spread to other parts of the body
or become more significant.
Finally, tertiary prevention is behavioral changes
that limit the progression of disease
and improve the quality of life after diagnosis.
So these could relate to physical activity,
or diet, or other factors.
The rationale for cancer preventions is that,
as we've discussed, cancer is a leading cause
of mortality and morbidity,
especially for people under age 85 years.
We also see that cancer therapies have improved,
but at the same time,
morbidity and mortality have not changed hugely.
We also see that effective cancer prevention
and control initiatives must incorporate
scientific validity, linguistic appropriateness,
and cultural competence.
And I really like this quote
because it really testifies to the importance
of designing prevention strategies for specific communities,
specific individuals, and really taking into account
all aspects of their identity.
So their biologic and genetic makeup,
as well as their practices related to diet,
their daily lives, their work, economic considerations
when designing things or programs
that will work for them to prevent cancer.
So to begin with, primary prevention
is essentially avoiding risk factors for cancer.
Primary prevention implicates
both individuals and structures.
Individuals can make healthy choices to prevent cancer,
but societies and communities can also put policies in place
that make it easier for individuals
to choose healthy behaviors or to avoid unhealthy behaviors.
It's also important to note that socioeconomic factors
are implicated throughout all levels of cancer prevention.
For example, if someone cannot afford fruits and vegetables,
they may be at a greater risk for cancer
because they're not able to consume a healthy diet.
Here we see some more examples of primary prevention,
including as we discussed in the last lecture,
the importance of avoiding infections
and limiting environmental risks like sunlight,
sources of radiation, and chemical carcinogens.
This great chart from your textbook
discusses a lot of common cancer risk factors
and the corresponding prevention strategies.
So for example, the hepatitis virus
can cause liver and biliary tract cancer,
and a key way to prevent that is to avoid exposure
to the virus or to be vaccinated against it.
And again we see the importance of socioeconomic factors,
because if you live in a community
where there's not primary care
or where you're unable to obtain the vaccination,
that's gonna limit your ability
to prevent liver and biliary tract cancer.
Similarly, if you do live in a community
where that vaccination is available
but you're not able to afford it,
or you don't have insurance coverage that will pay for it,
that's another barrier to being protected
against liver and biliary tract cancer.
Secondary cancer prevention
is early diagnosis and treatment.
We'll see later in the course
that many epidemiological studies
will analyze the correlation between
cancer outcomes and stage of diagnosis.
Cancer screening is a key area of focus
in cancer epidemiology, and methods vary
depending on country, cancer type, et cetera.
So here we see that any effective cancer control program
includes comprehensive cancer screening
for the timely diagnosis and effective treatment
of cellular lesions that could progress to invasive cancer.
So some examples of cancer screening techniques
are the mammogram, which is going to look for breast cancer,
the Papanicolaou or Pap test,
which is going to look for cervical dysplasia
or cervical cancer,
endoscopy, which can look at symptoms or signs
for Barrett's esophagus and stomach ulcers,
dental examination,
which can give show signs of oral leukoplakia,
colonoscopy, which can detect symptoms of colon cancer,
prostate specific antigen or PSA tests and ultrasound,
which can look at cancers of the prostate gland,
and dermatologic examination,
which can look at certain types of skin cancer.
We also see related to secondary cancer prevention
the importance of population screening programs.
So population screening programs can be used
in conjunction with skilled surgical techniques,
and this has been successful and continues to be successful
in reducing the mortality rates of certain cancers.
Population screening programs
can be difficult to implement on a national level,
but you might hear of a population cancer registry
or a national breast cancer screening campaign
using mammograms.
These can be expensive depending on the size of the country.
And it's important to think about communities
that are either able to access these programs
or unable to access them.
So commonly epidemiological studies might look at
the differences between rural and urban areas.
And a hypothesis might be that people in urban areas
are able to access screening more easily
because they live in close proximity to hospitals,
and health clinics, and primary care centers,
whereas people in rural areas might not be able to access
the same tools and techniques,
and thus might have lower rates of screening.
It's important that screening is accurate,
safe, inexpensive, and acceptable culturally
to the general public.
In high income countries, only about half of cancer patients
eventually die from the diseases.
But one thing that's hindering survival rates
in low and middle income countries
is that 80% of cancer victims
already have late stage, incurable tumors
when they're diagnosed.
Finally, we move to tertiary cancer prevention,
and this is the beneficial behavioral changes
that limit disease progression
and subsequent disability for patients
after they've been diagnosed for cancer.
So some examples of this are smoking cessation,
limiting alcohol intake, regular exercise, improved diet,
maintenance of optimum weight,
and compliance with prescribed treatment regimens.
This is also related to pain control and palliative care.
The goal of tertiary cancer prevention
is to increase survival rates
and improve the quality of life
among cancer survivors and their families.
And it's interesting because there's quite a few overlaps
between tertiary cancer prevention
and primary cancer prevention.
So for example, a lot of these unhealthy behavioral factors
like smoking and alcohol consumption
double as both primary and tertiary prevention strategies.
Finally, to touch upon cancer education,
the importance of educational programs cannot be overstated.
In different countries have implemented
cancer education programs for people at all stages of life.
So a push to incorporate cancer education
into elementary, middle, and high schools
can help people to understand the signs and symptoms
of common cancers that might afflict adolescents.
At the same time, when people at early ages
learn about different kinds of cancers,
they then can go home and speak with their family members
or other community members about the importance
of being aware of those types of cancers,
which in turn can lead to higher rates of elective screening
or higher general awareness of different cancers.
So as the slide says, these programs can promote awareness
of the risk factors and early symptoms of cancer
and provide accurate information on the cost, safety,
and accuracy of cancer screening tests.
These education programs are a big focus
in low and middle income countries
where access to highly-trained clinical staff,
or expensive treatments, or screening machines
might be, the expense of those techniques
and of that personnel might make it difficult
or might be a challenge to implementing programs
on a countrywide level.
And oftentimes, education programs can be implemented
at a lower cost and more widespread
if they're integrated into curriculums
in disparate regions of the country.