Download Is there a correlation between smoking and radon exposure

Is there a correlation between
smoking and radon exposure
as a cause of lung cancer?
Research Proposal
BIOL – 322
Dr. Ewart
Brianna Zerley
12/7/2012
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Abstract
Cancer is caused by rapidly dividing cells that grow out of control. These cells
develop due to damage to the DNA. Some cancer forms a tumor while others occur in
the blood. Cancer cells can spread to other parts of the body. Lung cancer causes more
death than any other cancer in men and women. Smoking is the leading cause of lung
cancer while radon exposure is the leading cause of lung cancer in non-smokers. In my
study I want to find out if smoking enhances the effect of lung cancer caused by radon
exposure or if radon exposure enhances the effect of lung cancer caused by smoking;
do the tumors grow larger? Does the tumor grow faster? Does the cancer spread faster
to other parts of the body? I will use a series of questionnaires and medical histories to
collect data then analyze my data using the student t-test to determine whether there is
a correlation between smoking and radon exposure as a cause of lung cancer.
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Background Information
Cancer is caused when cells rapidly divide in the body. Cancer cells develop due
to damage in the cell’s DNA. Most of the damaged cells in the body are repaired but
cancerous cells are not repaired and continue to divide and grow. Normal cells in adults
are produced to replace worn out or dying cells whereas cancer cells continually grown
and divide on their own. In the body there may be areas where pre-cancerous changes
occur. These changes often lead to cancer. As the cancer develops the cells may
produce chemicals that encourage blood vessels to attach to these cells so that they
can be continually nourished. These cells grown and form a tumor large enough to be
seen on an x-ray. Cells can then break away from the tumor and travel to other parts of
the body through the bloodstream or lymphatic system. The process of cancer cells
traveling to other parts of the body is called metastasis. When cells metastasize to
another part of the body they don’t become a new cancer. For example if cancerous
cells form a tumor in the lungs and some of the cells break off and metastasize to the
liver, it is still considered lung cancer not liver cancer since the cells originated in the
lungs.
Most lung cancers originate in the bronchi but can start in the trachea,
bronchioles or alveoli. Lung cancer often spreads before it is found. There are two
major types of lung cancer: small cell and non-small cell. There is also a third type that
is very rare in which the cancer has both small cell and non-small cell characteristics.
This type is called small cell/large cell carcinoma.
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Non-small cell lung cancer is the most common and accounts for 85-90% of lung
cancer patients. There are three subtypes: squamous cell carcinoma, adenocarcinoma
and large cell undifferentiated carcinoma. Squamous cell is usually caused by smoking
and is located close to the bronchi. Adenocarcinoma occurs on the outer region of the
lungs and has the best prognosis. Large Cell Undifferentiated carcinoma can occur in
any part of the lungs and has the poorest prognosis. Black men are 50% more likely to
develop non-small cell lung cancer than white men and women have a lower risk with
black women having a slightly higher risk than white women.
Small cell lung cancer accounts for 10-15% of lung cancer patients. Small cell
lung cancer is widely spread and grows rapidly. Surgery is rarely an option because of
how far the cancer has progressed before it is discovered. It often occurs in the bronchi
and smoking is normally the cause. It is also known as oat cell carcinoma and small cell
undifferentiated carcinoma (Swanton, 2006).
Smoking is the leading cause of lung cancer in the world. There are
approximately 40 different carcinogens found in cigarette smoke (Thoracic Imaging).
According to dictionary.com a carcinogen is anything that causes cancer. There are 69
chemicals in tobacco smoke that cause cancer including: arsenic, benzene, beryllium,
ethylene oxide and vinyl chloride. There are also other toxic chemicals in cigarettes that
cause cancer that include formaldehyde, benzoprene and toluene (CCI-NCI).
Carcinogens cause lung cancer. Soon after exposure to carcinogens, a few abnormal
cells appear in the lining of the bronchi. Gradually as exposure continues more and
more abnormal cells appear and some become cancer and tumor forming (Stop
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Smoking Programs). Genetic changes have also recently been found to cause cancer.
“In May 2008 there were new developments that identified a protein that is believed to
be the cause of the genetic changes that lead to lung cancer.” The protein FANCD2 is a
caretaker protein that corrects DNA damage and kills faulty or mutated cells. This
process normally prevents cancer. Tobacco smoke slows the production of FANCD2 and
other caretaker proteins. This in turn provides an easy way for DNA to be damaged. If
enough cells mutate and reproduce from the shortage of FANCD2, cancer forms
(LIVESTRONG.COM).
After smoking radon exposure is the second leading cause of lung cancer deaths.
The Harvard center for risk analysis ranked the inhalation of radon gas the most
important potentially fatal hazard in the home. Radon is a naturally occurring and
cancer causing radioactive gas that you can’t see, smell or taste. Radon is produced
form the natural breakdown of Uranium found in igneous rock and soil and also can be
found in the water supply. The US Environmental Protection Agency classified radon as
a class A carcinogen. This means that it is a pollutant that has enough evidence that
indicates it causes cancer in people. Radon can enter and accumulate in homes as a
result of the differential pressure between homes and the ground under them. To enter
the body radon attaches to dust particles that are then inhaled. The radioactive
particles attached to the dust will then lodge in the bronchioles and emit ionizing
radiation to the surrounding tissue. The radiation also interacts with bronchial epithelial
cells damaging their DNA and causing neoplasia (Duckworth, Frank-Stromborg,
Oleckno, Duffy, & Burns, 2002). Radon can cause different types of lung cancer such as
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squamous cell carcinoma, small cell carcinoma, adenocarcinoma and large cell
carcinoma. Other respiratory effects can occur from radon exposure such as
emphysema, pulmonary fibrosis, chronic interstitial pneumonia, silicosis and respiratory
lesions (University of Minnesota).
Aims
My main aim is to determine if there is a correlation between radon exposure
and smoking as causes of lung cancer. Other aims I have are: find out if these
exposures increase tumor size, increase the rate of growth of the tumor, or if the
cancer spreads to other parts of the body faster.
Methods
I will use a series of questionnaires and medical history to help collect data for
my study. To obtain my sample of patients I will perform an online survey on a variety
of multiple hospital’s websites so I can get a good amount of responses. I will also
advertise my study in an attempt to find as many patients for my study as possible. I
want my sample to include 200 lung cancer patients. Of these 200 patients I want 100
patients whose lung cancer was specifically caused by smoking and 100 patients whose
was specifically caused by radon exposure. I want to make sure that these patients
have been told directly that the cause of their lung cancer was one of these two so I
can minimize variation in my study and acquire accurate results. I will then have these
patients sign a consent form agreeing to participate in my study and along with the
consent form I will also explain the study and what information I hope to gather.
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After finding my sample of patients I will collect their medical history. I will also
be sending out a primary questionnaire. This primary questionnaire will include
information on their cancer. In the first part I will ask about their tumor size upon
diagnosis, where their cancer was originally located when diagnosed, and if it has
spread to any other organs or tissues. In the second questionnaire it will ask how long
it has been since the patient has had an exam, what the size of their tumor is now and
if it has metastasized anywhere else in the body since their original diagnosis.
Next, I will give out a secondary questionnaire about the patients’ smoking
history. The questions on this questionnaire will include whether they are a smoker or
not, how long have they been smoking, how much they smoke each day, if they are a
past smoker and if they have had second hand smoke exposure.
After both of the questionnaires have been given I will then send out radon
testing kits for the patients to test their homes with. I want to gather information on
the radon levels in their homes to see if those patients with cancer caused by smoking
have had accelerated tumor growth or metastasis.
Data Analysis
After all the data has been collected from the medical histories, questionnaires,
and radon testing kits, I will separate the patients in to four groups to observe my data.
These four groups will consist of two control groups and two test groups. The first
control group will consist of patients whose cancer was caused by smoking and had a
normal level of radon in their homes that will be compared to a test group of patients
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whose cancer was caused by smoking and had abnormal levels of radon in their homes.
The second control group will be the patients whose cancer was caused by radon
exposure but don’t have a smoking history. This group will be compared to the second
test group which consists of patients whose cancer was caused by radon exposure and
do have a smoking history.
I will then use a t-test to determine the before and after size of the patients’
tumor sizes and their metastasis and compare my test groups to their corresponding
control groups. I will also be able to use another t-test to determine whether the
amount of cigarettes smoked had any effect on the growth rate and metastasis of the
cancer.
Conclusions
After my data analysis I can determine whether smoking and radon exposure are
directly correlated and can affect the size or metastasis of a tumor. I will also be able to
determine whether the amount of cigarettes smoked by the smokers had an effect on
the growth and metastasis of a tumor.
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References
Duckworth, L., Frank-Stromborg, M., Oleckno, W., Duffy, P., & Burns, K. (2002).
Relationship of perception of radon as a health risk and willingness to engage in
radon testing and mitigation. Oncology Nursing Forum, 29(7), 1099-1107.
Doi:10.1188/02.ONF.1099-1107
Harms of Smoking and Health Benefits of Quitting - National Cancer Institute. (n.d.).
Comprehensive Cancer Information - National Cancer Institute. Retrieved
December 6, 2012, from
http://www.cancer.gov/cancertopics/factsheet/tobacco/cessation
How Can Smoking Cause Lung Cancer? | LIVESTRONG.COM. (n.d.). LIVESTRONG.COM
- Lose Weight & Get Fit with Diet, Nutrition & Fitness Tools | LIVESTRONG.COM.
Retrieved December 6, 2012, from http://www.livestrong.com/article/22696can-smoking-cause-lung-cancer/
Radon: Harmful Effects. (n.d.). University of Minnesota Environmental and Occupational
Health. Retrieved December 6, 2012, from
www.enhs.umn.edu/current/5103_spring2003/radon/radonharm.html
Smoking - Lung Cancer Facts. (n.d.). Stop Smoking Programs, Products and Quitting
Aids. Retrieved December 6, 2012, from http://www.stop-smokingprograms.org/lung-cancer.html
Smoking and Lung Cancer. (n.d.). Thoracic Imaging. Retrieved December 6, 2012, from
http://www.chestx-ray.com/smoke/smoke.html
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Swanton, J. (2006). Quick Facts on Advanced Cancer: What You Need To Know—
Now/Quick Facts on Lung Cancer: What You Need To Know—Now. Library
Journal, 131(18), 103.