PRELIM 3: LUNG CANCER Overview (21)

What are some reasons that people perceive smoking to be "good?"

-Acts as a depressant, calms you down -Contains stimulant -Contains appetite suppressant -Role models who smoke

The most common cancers are:

-Breast cancer -Lung and bronchus cancer -Prostate cancer -Colon and rectum cancer -Melanoma of the skin -Bladder cancer -Non-Hodgkin lymphoma -Kidney and renal pelvis cancer -Endometrial cancer -Leukemia

The number of deaths from lung cancer is also going down. How do we know someone has died from lung cancer?

-Death certificate -Diagnosis of lung cancer -Someone who is initially diagnosed with a cancer of some sort and is eventually determined that the cause of death was from lung cancer

What are 4 ways that cancer cells differ from normal cells?

-Grow in absence of signals telling them to grow. Normal cells only grow when they receive such signals -Ignore signals that normally tell cells to stop dividing or to die -Invade into nearby areas and spread to other areas of the body. Normal cells stop growing when they encounter other cells, and most normal cells do not move around the body -Tell blood vessels to grow toward tumors. These blood vessels supply tumors with oxygen and nutrients and remove waste products from tumors.

What are 3 reasons why we should focus on lung cancer?

-It is the second most common form of cancer -It is preventable -It is, increasingly, a public healthy success story

Linking smoking to lung cancer: The Doll-Hill Study Describe the first research problem

-Lung cancer might be caused by all sorts of things. We will use location (e.g. air pollution) as an example -Lung cancer might be correlated with location or educational attainment. Suppose: --> Smoking and lung cancer are correlated --> Low education and lung cancer are correlated --> Location and lung cancer are correlated -If we observe a correlation between smoking and lung cancer, is it because smoking causes lung cancer or is it the fact the people most likely to smoke (low education) are living in places where they are more likely to get lung cancer (location)

Describe the second research problem

-The relationship between smoking (or indeed any environmental factor) and lung cancer is not instantaneous (most cancers appear later in life) -We need to identify smokers and non-smokers in a population and follow them over many years -We need to correctly identify who dies and what their cause of death is

Doll and Hill resolved all of the problems by using British doctors as their prospective cohort. Why was this a good idea? (1)

1) Doctors all have the same occupation, allowing us to ignore the potential confounding effects of occupation (and thus exposure to carcinogens) on lung cancer 2) Doctors in Britain had all attended university 3) At the time, most doctors were employed by the public sector and thus had broadly similar incomes 4) At the time of the study, most doctors cam from middle class families and so family background was similar 5) What differentiated study participants was whether they consumed tobacco products, and if so, in what quantity

Doll and Hill resolved all of the problems by using British doctors as their prospective cohort. Why was this a good idea? (2)

6) All doctors in Britain were listed on something called a "Medical Register" -- literally, a list of who is a doctor and where they lived. When a doctor dies, their name is removed from the register. Thus, Doll and Hill could track who died, and when 7) When someone dies, a death certificate is issued, which include the cause of death --All this mean that after doing their initial survey -- writing to every doctor in the country in October 1951, Doll and Hill simply needed to track these deaths and their causes over time. They did not have to re-survey their study participants. They could then cross-tabulate these against the use of tobacco products.

What does research problem 1 imply?

A cross-sectional design will not work well

What are some reasons that people perceive smoking to be "bad?"

Class: -Cost -Advertisements about the effects of smoking on health -lung cancer Hoddinnott: Randomized control trial -- treatment and control group; never has been done because it is unethical Relates to Doll-Hill study

What are the three broad sets of factors that cause cancer?

Environmental -Radiation -Chemical carcinogen exposure -Exposure to sun UV (through outside work) Behavior -Alcohol -Tobacco -Certain foods -Excessive exposure to sun UV (through tanning) Genetic -Some cancers have a genetic origin, but these comprise a relatively small fraction of all cancers

For people who are really young, childhood cancer is very rare. As we get older, the likelihood that we get diagnosed with cancer rises steeply.

Graph

Over the last 20 years, the rate of new cancers has decreased (lung and bronchus)

Graph

Cancer mortality differs by race. Racial disparities have been declining, but what race is the highest and lowest?

Highest in African American men (227.3 per 100,000) Lowest in Asian/Pacific Islander women (85.6 per 100,000)

Incidence of cancer differs across the country and is not uniform. Where is cancer most prevalent and why?

Highest in the deep south, Appalachia, and parts of New England Deep south and Appalachia are the poorest parts of the country Appalachia and parts of New England are (rural on average?) and the populations are old

More specifically, how does cancer develop when the body's normal control mechanisms stops working?

Instead of dying, these cells grow out of control, forming new, abnormal cells. A tumor is a tissue mass of these cells. Some cancers lead to tumors (lung cancer) but not all do (leukemia).

What were some of the key results from the study, shown in the table?

Lung cancer in comparison to other cancers had a higher rate of getting cancer when individuals smoked in comparison to non smokers. The amount of tobacco smoked influenced likelihood of getting cancer.

What happens when the genetic material of a cell (DNA) is damaged?

Mutations can arise, potentially disrupting normal growth and division. An accumulation of mutations can turn normal cells into precancerous cells, which sometimes multiply and evolve into cancer cells. Cancer is a result of the accumulation of these cells

How many types of cancers are there? In 2018 in the US, how many new cancer cases were reported and how many people died of cancer? For every 100,000 people, how many cases and deaths were reported?

Over 200 different types 1,708,921 and 599,265 436 new cases and 149 deaths

What three types of cancers account for about 43% of all cancers diagnosed in men in 2020? For women, what are the three types of cancer accounting for about 50% of all new cancer diagnoses in 2020?

Prostate, lung, and colorectal Breast, lung, and colorectal

How do cells behave in a healthy body?

They grow and divide in a controlled, orderly fashion, replacing those that have grown old or have been damaged and die (a process called apoptosis)

How did Doll and Hill resolve both problems?

Using a prospective cohort study design

What does research problem 2 imply?

We need to follow the same people over a period of time, which is hard to do. People might move or decide that they do not wish to continue to be part of the study.

Disaggregating cancer incidence and mortality: The incidence and prevalence of cancer differs across numerous dimensions including what?

age, sex, race, and ethnicity

Cancer occurs when this natural process goes ___

awry

Differences in cancer mortality by sex, race, and ethnicity is a consequence of differences and disparities in ___ ___, ___, ___ to ___ ___ (prevention, screening and treatment) and types of cancer

behavior factors, environments, access to healthcare

Further, as we age, we have more exposure to the ___ and ___ factors that cause cancer

behavioral, environmental

Why focus on lung cancer? Understanding what the causes of lung cancer are, why its incidence and mortality is falling, and why this differs by sex, age, race, and ethnicity requires both a ___ and ___ ___ perspective

biological, social science

As we age, there is more time for ___ in our cells to build up, and so more chance that some of this ___ might eventually lead to cancer

damage, damage

Describe a prospective cohort study

follows over time, groups of individuals who are alike in many ways but differ by a certain characteristic. We then see if there is a relationship between that certain characteristic and our outcome(s) of interest

Cancer is the second leading cause of death in the US, only exceeded by what? ___ out of every four deaths in the US is due to cancer

heart disease 1 out of every four

Cancer mortality by sex, race and ethnicity: The cancer mortality rate is higher for ___ than for __ What are the cancer mortality rates for both genders?

men, women 189.5 per 100,000 men 137.5 per 100,000 women