USING LOW DOSE COMPUTED TOMOGRAPHY IN LUNG CANCER SCREENING
by
Hazim Ogorban
M.B.Ch.B, Tripoli University, Libya, 2003
Submitted to the Graduate Faculty of
the Multidisciplinary MPH Program
Graduate School of Public Health in partial fulfillment
of the requirements for the degree of
Master of Public Health
University of Pittsburgh
2013
UNIVERSITY OF PITTSBURGH
GRADUATE SCHOOL OF PUBLIC HEALTH
This essay is submitted
by
Hazim Ogorban
December , 2013
Essay Advisor:
David Finegold, MD
Director, Multidisciplinary MPH Program
Professor, Department of Human Genetics
Graduate School of Public Health
University of Pittsburgh
______________________________________
Essay Reader:
Joel Weissfeld, MD, MPH
Associate Professor
Department of Epidemiology
Graduate School of Public Health
University of Pittsburgh
______________________________________
Essay Reader:
Thomas Songer , PhD
Assistant Professor
Department of Epidemiology
Graduate School of Public Health
University of Pittsburgh
______________________________________
ii
Copyright © by Hazim Ogorban
2013
iii
David Finegold, MD
USING LOW DOSE COMPUTED TOMOGRAPHY IN LUNG CANCER SCREENING
Hazim Ogorban, MPH
University of Pittsburgh, 2013
Abstract
More people, in the United States and worldwide, die from lung cancer than breast, colon, or any
other type of cancer. Although, efforts to reduce tobacco smoking have decreased incidence rates
in the U.S, lung cancer remains a public health issue that needs an effective intervention. Results
from the National Lung Screening Trial (NLST) demonstrate that screening high risk individuals
with low dose computed tomography (LDCT) can have a significant impact on mortality rates of
lung cancer. However, implementing a lung screening program in real world practice could be a
challenging task. Therefore, medical and public health institutions should be prepared with
necessary resources, adhere to a standard practice for lung cancer screening, decrease health care
disparities, and enhance public participation. This review presents some key statistics for lung
cancer in the U.S, an overview of lung cancer screening studies and the impact of radiological
settings and lung nodule management protocols in detecting cancer lesions, and discusses issues
related to implementation of a national screening program.
iv
TABLE OF CONTENTS
1.0
2.0
INTRODUCTION............................................................................................................... 1
1.1
BACKGROUND ..................................................................................................... 1
1.2
LUNG CANCER STATISTICS IN THE U.S ..................................................... 2
1.2.1
Incidence .......................................................................................................... 2
1.2.2
Mortality .......................................................................................................... 3
1.2.3
Survival Rates................................................................................................. 5
LITRETURE REVIEW…………………………………..…………………………………………… 5
2.1
OVERVIEW OF LUNG CANCER SCREENING STUDIES ............................. 5
2.1.1
The National Lung Screening Trial (NLST)……………………………………….. 5
2.1.2
The Dutch-Belgian Randomized Lung Cancer Screening Trial …………...... 6
2.2.3
Other randomized clinical trials and observational studies………………….…7
2.2
IMPLEMENTATION…………………………………………………………………………8
2.2.1 Selection criteria…………………………………………………………………………….10
2.2.2 A multidisciplinary health care team …………………………………………………11
2.2.3 Lung nodule diagnosis and management ………………………………………..…..12
2.2.4 CT settings and quality assurance …………………………………………………….13
2.2.5 False positives and invasive procedures ……………………………………………..14
v
3.0
DISCUSSION.....................................................................................................................15
BIBLIOGRAPHY ....................................................................................................................... 18
vi
LIST OF FIGURES
Figure 1: Age-adjusted incidence rates of lung & bronchus cancer in the United States.............3
Figure 2: Age-adjusted mortality rates of lung & bronchus cancer in the United States…………4
Figure 3: Interactions among different health institutions and stakeholders in lung cancer
screening……………………………………………………………………………………...………………..…...11
1.0 INTRODUCTION
1.1 BACKGROUND
In the United States, lung cancer is the leading cause of cancer death among men and women. In
2010, 201,144 individuals were diagnosed and 158,248 died from lung cancer [1]. According to
the American Cancer society, there will be an estimated 228,190 new cases and 159,480 deaths
from lung cancer in 2013 [2]. When compared to breast and colorectal cancers, death rates from
lung cancer exceeds the death rate of both previous cancers combined. For breast cancer, the
estimated new cases and death rates in 2013 are 234,580 cases and 40,030 deaths, respectively.
And colorectal cancer is estimated to account for 142,820 new cases and 50,830 deaths in the
same year [3]. The latest U.S available data indicate that lung cancer is accountable for
approximately 14% of all newly diagnosed cancer cases. Most of these new patients (31.4%) are
between 65 and 74 years old, and the median age of death due to lung cancer is 72 years of age
[4]. The 5-year survival rate for lung cancer is 17%, in breast cancer the rate is 90%, and 65% for
colon cancer [3]. Despite the poor prognosis and survival rates for lung cancer, detecting an early
stage tumor has a better chance to be treated than late stage disease [2].
The effectiveness of various approaches for detecting and treating early lung cancer has been a
major public health interest for many years [5]. In 2011, results from the National Lung
Screening Trial (NLST) showed a 20% decrease in lung cancer mortality in individuals screened
with a low dose CT (LDCT) compared to a control group receiving regular chest x-rays. The
study also reported that, 320 individuals needed to be screened in order to prevent 1 person from
lung cancer death [6]. Whether a national lung screening program follows the NLST or a similar
protocol, the major concern, will be effectiveness in practice, associated with lowered lung
cancer mortality, improved cancer outcomes, and minimum harm.
1
1.2 LUNG CANCER STATISTICS IN THE UNITED STATES
1.2.1 Incidence
Data from the National Cancer Institute (Surveillance, Epidemiology, and End Results Program)
show that between 2006 and 2010, age-adjusted U.S lung cancer incidence rate for all ages, all
races, male and female was 61.4 per 100,000 persons. Rates were 356 and 18.6 per 100,000 for
person’s ≥ 65 and ≤ 65 years, respectively. Males aged 65 and over had an incidence rate of
443.3 per 100,000, while the rate in female was 294.6 per 100,000. In general, the black (male
and female) race had a higher incidence rate than the white race. However, black males had
higher incidence rates than white males and white females had higher rates than black females
[7].
Age specific incidence rates for both sexes between 2006 and 2010 were below 200 per 100,000
for both age groups 55-59 years and the age group 60-64 years. The 65-69 years age group and
the 70-74 years age group had an incidence rate of 267.4 per 100,000 and 359 per 100,000
individuals, respectively. The rate was above 400 for both age groups 75-79 years and 80-84
years [7]. Figure (1) shows the U.S age-adjusted (2000 U.S standard population) lung &
bronchus cancer incidence rates by gender, race, and age group from 1973 to 2010, generated
from the Surveillance, Epidemiology, and End Results Program, using SEER*Stat software
version 8.1.2 [8].
2
Incidence
400
350
Rate per 100,000
300
65+ years
250
55-64 years
200
Male
Black
150
White
100
Female
Under 55 years
50
2009
2007
2005
2003
2001
1999
1997
1995
1993
1991
1989
1987
1985
1983
1981
1979
1977
1975
1973
0
Year of diagnosis
Figure (1) Age-adjusted incidence rates of lung & bronchus cancer in the United States based on
Surveillance, Epidemiology, and End Results Program data released in April 2013.
1.2.2 Mortality
The age adjusted U.S lung cancer death rate between 2006 and 2010 for all ages, all genders, and
all races was 49.5 per 100,000 persons. The mortality rate for those under 65 years of age was 14
per 100,000 and the rate was 294.3 per 100,000 for people 65 years and older. Males had higher
rates than females and black males aged 65 and older had the highest death rates. Otherwise
there was a slight difference between white (both genders) and black (both genders) races. The
age specific mortality rate between 2006 and 2010 for both male and female, all races was 120
3
per 100,000 for individuals between 60 and 64 years of age, 200 per 100,000 for the age group
65-69 years, 280 per 100,000 for those between 70 and 74 years, and above 300 per 100,000 for
all the other older age groups [7]. Figure (2) shows the U.S age-adjusted (2000 U.S standard
population) lung & bronchus cancer mortality rates by gender, race, and age group from 1969 to
2010, generated from the Surveillance, Epidemiology, and End Results Program, using
SEER*Stat software version 8.1.2 [9].
Mortality
350
Rate per 100,000
300
250
65 + years
200
55-64 years
Male
150
Black
100
White
50
Female
Under 55 years
1969
1971
1973
1975
1977
1979
1981
1983
1985
1987
1989
1991
1993
1995
1997
1999
2001
2003
2005
2007
2009
0
year of death
Figure (2) Age-adjusted mortality rates of lung & bronchus cancer in the United States based on
Surveillance, Epidemiology, and End Results Program data released in April 2013.
4
1.2.3 Survival Rates
The five-year survival rate for lung cancer cases diagnosed at an early stage (localized within the
lung) is 53.3%. For regional lung cancer (cancer spread to nearby lymph nodes) the rate is 26 %
and the five-year survival rate for late stage disease (cancer spread to other organs) is 3.9%.
However, only 15% of malignant lung cancer cases are discovered at an early stage and 57%
diagnosed at a late stage [4]. The five-year survival rate for lung cancer between 1975 and 1977
was 12.2% and between 2003 and 2009 the rate was 17.5%. This slight improvement in survival
is much less than that observed for other cancers. For example, the five-year survival rate of
breast cancer between 1975 and 1977 was 74.8% and the rate increased to 90.3% between 2003
and 2009. For colon cancer the rates improved from 50.6% to 65.4% between the years 19751977 and 2003-2009. Likewise, prostate cancer’s five-year survival rate increased from 67.8% to
99.7% [7].
2.0 LITERATURE REVIEW
2.1 OVERVIEW OF LUNG CANCER SCREENING STUDIES
2.1.1 The National Lung Screening Trial (NLST)
The NLST is the largest randomized clinical trial (RCT) for lung cancer screening. 53,454
individuals were enrolled in the study, 26,722 of them were randomly assigned to a low dose CT
(LDCT) group comparing them to another group that received chest-x-ray screening. Annual
screening for 3 years was conducted with a 94% follow up rate in the first year and a 92% in the
second year [6]. Screening was performed in multiple centers, with different brands of imaging
5
equipment. The main characteristics assessed were nodule diameter. A non-calcified nodule
equal or more than 4mm in diameter was considered a positive result. All the CT scanners used
satisfied NLST protocol requirements, including detector collimation of 2.5 mm or less, a
reconstruction slice width 1-3.2 mm, and a scanning time of less than 25 seconds. The NLST
showed a 20% decrease in lung cancer mortality [6, 10].
2.1.2 The Dutch-Belgian Randomized Lung Cancer Screening Trial (NELSON)
The NELSON study is the largest RCT for LDCT screening in Europe, which compared CT
screening with usual care (no screening). A total of 15,822 participants, 7557 of them were
screened by LDCT in 3 rounds, year 1, 2 and 4 and followed for 10 years since randomization.
Screening was conducted in 4 sites; with 16-detector CT Siemens and Philips scanners. Scanning
was performed in a spiral mode, 1 mm slice thickness, and a 0.7 mm reconstruction interval.
Nodule diameter and volume were assessed and volumetric software was used to help in
diagnosis. Images were read by 2 and sometimes 3 radiologists with experience in reading
thoracic CT scans [11, 12]. A test was positive if a non-calcified nodule was more than 500 mm3
or had a 25% increase in volume (volume doubling time) in less than 400 days, and intermediate
if it was 50-500 mm3 or had a volume doubling time (VDT) from 400-600 days. In the LDCT
group, 2.6% of scans were positive at baseline and 1.8% at the second screening round.
Participants who had an intermediate test at baseline and had a positive result in a 3 month
follow-up CT scan, were counted in the 2.6%. The study had a 95% adherence at baseline and
92% at the second round. Lung cancer detection rates were 0.9% at baseline and 0.5% at the
second round respectively [11, 12].
6
2.2.3 Other randomized clinical trials and observational studies
The Pittsburgh Lung Screening Study (PLuSS):
This was an observational study that enrolled 3642 participants. Subjects received an annual lung
CT scan and were followed for 3 years. Radiologists measured nodule diameter as the main
characteristic to classify lung nodules. After 3 years from the first CT scan performed, the study
identified 80 (2.2%) cases of primary lung cancer; one-half of those patients had stage I nonsmall cell cancer. Although, the study showed high rates of early stage cancer detection, there
was a large number of people, 36 individuals (1% of the total screened), that underwent invasive
procedures, such as thoracotomy, video assisted thoracoscopic surgery, mediastinoscopy, and
median sternotomy, which later on were found to have benign lesions [13]. In 2011, the PLuSS
team reported that they accumulated more than 150 lung cancer diagnosis in subjects who
enrolled in the study [14].
The Danish Randomized Lung cancer CT Screening Trial (DLCST):
The DLCST included 4014 individuals randomized to annual screening or no screening (usual
care) for 5 rounds [15]. The study was performed in one center using Philips CT scans, 1-3 mm
slice thickness, and 1-1.5 mm reconstruction interval. Images were assessed according to
diameter and volume by 2 board certified radiologists and used the same volumetric software
used in the NELSON study [10, 12& 15]. In the screening group 69 lung cancers were diagnosed
throughout the study compared with 24 in the control group, which was statistically significant
(P <0.001), with an overall cancer detection rate of 0.7% [16].
7
The DANTE & ITALUNG studies:
A RCT conducted in Milan, Italy, the DANTE (Detection and Screening of Early Lung Cancer
by Novel Imaging Technology and Molecular Essays) trial enrolled males only aged 60 to 75
years old. 1276 subjects received an annual LDCT for 5 years and 1196 in the control group had
annual medical examinations. Screening was performed in 3 sites with a Philips scanner, 5 mm
thickness, 3 mm reconstruction interval, and nodule diameter was the main characteristic
assessed [12, 17]. Another study conducted in Italy, the Italian Lung study (ITALUNG), is a
RCT that included 1613 in the LDCT group, 1593 in the control group (no screening), and 4
annual screening rounds. The trial had 3 screening sites, using Siemens and General Electric CT
scans, with slice thickness of 1-3 mm, and a reconstruction interval 1-1.5 mm [12, 18]. Two
board certified radiologists with 5 or more years of experience read each CT image
independently, assessing nodule diameter but not volume plus other characteristics. The study
results after baseline screening show that 30.3% of individuals in the screened group had positive
results. The positive results decreased during the other screening rounds by almost 50%, but still
higher than most RCT conducted during that time [12, 18]. This high rate of positive results
usually leads to more follow up images, invasive procedures, and more false positive cases.
2.2 Implementation
Lung cancer screening trials conducted in the USA and Europe show different results, regarding
cancer detection rates, reduction in mortality rates, and number of false positive results. While
the NLST study demonstrated a significant decrease in lung cancer mortality and all-cause
mortality, it also had a high rate of false positive and a positive predictive value < 4% [6, 19].
Studies such as the NELSON study, the second largest clinical trial after the NLST, had a higher
8
positive predictive value, 35.7% at baseline and 42.4% at the first round of screening (one year
after randomization) [19]. The final results from the NELSON trial are expected in 2016, which
will be very important for the future of lung cancer screening, especially in European countries.
Many studies showed no difference in lung cancer mortality rates between the LDCT group and
the control group, most likely due to small number of participants compared to the NLST and the
NELSON studies. Therefore, it will be extremely important to follow a highly structured system
similar if not better than that of the NLST study, to achieve a successful LDCT screening
program in the US or any other country [20]. Some of the challenges that can face LDCT
screening implementation in any regional or national health care system are:
1. Selection criteria for individuals screened.
2. Presence of a multidisciplinary health care team at screening centers.
3. Forming an efficient protocol for lung nodule diagnosis and management.
4. Unifying CT settings and quality assurance in multiple screening centers.
5. Reducing false positives and minimizing invasive procedures.
2.2.1 Selection criteria
To increase benefit and decrease harm from LDCT screening, the targeted population should
contain high risk individuals. The NLST study criteria used to identify those eligible for
screening included, age (55 to 74 years), a history of 30 pack-years of smoking in current
smokers and former smokers who stopped smoking in the last 15 years [6]. Tammemagi et al.
used a modified model of the Prostate, Lung, Colorectal, and Ovarian (PLCO) cancer screening
trial and re-examined the selection criteria of the NLST study. An estimated 12 deaths due to
lung cancer would have been avoided if the modified PLCO (M2012) risk prediction model was
9
used [21]. Proving that sensitivity for lung cancer detection can be improved using a more
complex risk model. Predictors used in this model are age, level of education, body mass index
(BMI), chronic obstructive pulmonary disease (COPD), family history of lung cancer, smoking
status, duration of smoking, smoking quit time, and smoking intensity [21, 22].
2.2.2 A multidisciplinary health care team
Developing a lung cancer screening program, needs a well-established infrastructure and a team
of experts in different medical fields. More than one hospital and health care institute are
expected to work together using a standardized protocol in managing pulmonary nodules and
lung cancer disease [19]. The International Association for the Study of Lung Cancer (IASLC)
recommends that a multidisciplinary team should be involved in LDCT screening, and medical
centers should have the capability to provide the appropriate imaging procedures and the
equipment needed in minimal and invasive procedures, such as video-assisted thorascopic
surgery, which has lower morbidity and mortality, and leads to less hospital stay than open
surgeries [22, 23].
Primary care physicians and physician assistants will have a major role in selecting eligible
patients and managing lung nodules. For this reason, it is very important that they are educated
and regularly updated with the latest evidence based information regarding lung cancer
screening, its benefit, and the risks involved. They should also be provided with all the necessary
resources [19]. Most likely, there will be a huge number of people living in rural areas and
underserved communities, who will face difficulties in showing up for screening and follow up
sessions. Therefore, large medical centers with the proper surgical and technical facilities should
cooperate with family practices and health care professionals working in those areas, to ensure
10
that most patients, if not all, receive sufficient care, regular follow up, and required treatment
when needed. Figure (3) illustrates how institutions and stakeholders might integrate with one
another in a lung cancer screening program.
Primary Health
Care Centers
High risk
individuals
Specialized Medical
Institutions
General
population
CT scan
screening
centers
Individuals
needing follow
up
Invasive
procedures and
treatment
centers
Public health and research
institutions
Figure (3) Interactions among different health institutions and stakeholders in lung cancer
screening.
11
2.2.3 Lung nodule diagnosis and management
Some of the main characteristics used to diagnose and classify pulmonary nodules are, nodule
size, location, morphology, calcification and anatomic position [6, 10-13]. Probably the most
important predictor of malignancy is the size of a nodule [24]. Many randomized clinical trials
used nodule diameter (2 dimensions) to assess size. Other studies, such as the NELSON trial,
used volumetric software to measure nodule volume (3 dimensions). Nodules between 50500mm3 were classified as intermediate and those more than 500mm3 were positive. Intermediate
results were followed after 3 months by another CT scan. Nodules that had a volume doubling
time (VDT) < 400 days were suspicious for malignancy and required additional diagnostic
workup [11]. In the NLST study, a non-calcified nodule more than 4mm in size was considered
positive [6]. When using a 2 dimensional diameter measurement protocol, the maximum
diameter of irregular shaped nodules is used to calculate their size. This can lead to
overestimating the true size of a nodule and cause more false positive cases [22].
Results from Heuvelmans et al. show that, during follow-up of suspicious nodules, all the fast
growing malignant tumors had a VDT equal to 232 days or less. If this VDT is used to follow
and manage lung nodules it could decrease false positive referrals [25]. 3 dimension (3D)
volumetric measurements evaluate the whole structure of a lung nodule. For this reason, they can
give more accurate results than 2 dimension (2D) measurements [22]. The decision to use a 3D
software analysis, a 2D measurement protocol, or even both in lung cancer screening programs
will definitely have a crucial role in diagnosing and managing pulmonary nodules and lung
cancer mortality rates in the future.
12
A study that evaluated volume doubling times in 63 non-small cell lung cancers from the
Pittsburg Lung Screening Study (PLuSS), compared cancers that were visible as suspicious
nodules at baseline screening with those that were discovered during follow up. Some of the
main results from this study are; (1) the slow growing cancers (doubling time > 365 days) were
mostly adenocarcinoma/bronchi alveolar carcinoma type of lung cancer (86.7%), while the fast
growing ones (doubling times < 183 days) were mainly squamous cell lung cancer (60%); (2)
two-thirds of the cancers that were visible as nodules at baseline rounds had a slow doubling
time and only 10% of cancers that were first visible during a follow up CT scan had a slow
doubling time. These findings are useful in managing lung nodules during follow up sessions
[14].
2.2.4 CT settings and quality assurance
Conducting a large screening program that involves many medical centers, a large number of
technicians, and multiple imaging procedures will probably have some degree of technical
problems and errors. Therefore, it will be extremely important to constantly monitor the
screening process from the beginning and detect any imaging defects to ensure high quality
results and minimize radiation exposure [26]. Screening in the NLST was performed in 10
centers using different CT brands [6, 26]. Gierada et al. conducted a study to assess the effect of
implementing an imaging quality assurance program on CT image quality of the NLST study.
The study identified low rates of quality defects, indicating that applying a quality assurance
program in large multicenter trials can reduce technical errors [26].
Results from a study that examined the effect of using different CT slice thicknesses (1.25mm,
2.5mm & 5mm) and 2 different software packages on lung volume measurement show that,
13
small lung nodules (3-10mm) were more likely to have different volume measurements than
large nodules (>15mm) on both software systems when different CT slice thicknesses were used.
The study also mentions that smaller nodules are better analyzed with thinner (1.25mm) CT
section thickness. And different volume measurements were observed for all nodules (small and
large) when different software packages were used at a 2.5 mm section thickness. Therefore, it is
best to use the same type of software and CT settings when following patients with a history of a
suspicious lung nodule [27].
Assessing nodule size by measuring its volume and VDT is demonstrated to be a useful
diagnostic tool to differentiate between benign and suspicious lung nodules [28, 29]. However,
accuracy of volumetric measurement depends on many factors, such as CT settings, type of
software used, radiologists reading the image, and nodule characteristics [28-30]. Wang et al.
evaluated the effect of low dose CT reconstruction settings on volumetric measurement. Their
study found that using a 1mm section thickness with soft kernel reconstruction settings was
superior to a 2mm section thickness in volume measurement repeatability. To avoid incorrect
assessment of VDT when following a lung nodule over time, the authors recommend using the
same CT reconstruction settings [28].
2.2.5 False positives and invasive procedures
Bach at al. conducted a systematic review on the benefits and harms of CT screening for lung
cancer. The review reported that nearly 20% of individuals enrolled in 8 randomized control
trials and 13 cohort studies had a positive result in each screening round, ranging from 3% to
30% in RCTs. Most of these positive results were benign, but led to further workup and invasive
procedures [31]. In the NLST study, 27% of individuals in the LDCT group at baseline had a
14
positive result with a false positive rate of 96% and after 3 screening rounds 40% of subjects had
a suspicious CT scan finding [32]. The positron emission tomography (PET) was needed in 5.5%
of total individuals screened in the NLST. While invasive procedures, such as needle biopsy and
bronchoscopy were conducted in 1.2% of individuals who were found to have benign lesions, in
both the NLST and the NELSON study. Rates of invasive surgical procedures were 0.7% in the
NLST and 0.6% in NELSON [31]. However, according to the results from the NLST study, the
rate of major complications due to invasive procedures were only 0.06% in patients who had a
false positive result and 11.2% in those diagnosed with lung cancer [6]. In 2011, Nair et al
published an article in the European Society of Radiology, mentioning that the rate of invasive
procedures practiced during nodule management in lung screening studies ranged from 0.8% to
7.5% [10].
3.0 DISCUSSION
There is no doubt that lung cancer is a major public health problem [1-4]. And the association
between tobacco smoking and lung cancer is well known. The purpose of this review was to
examine the latest evidence based practices and CT settings in lung cancer screening, and how
they might impact the future of this devastating disease. Since the release of the NLST results, a
number of recommendations and guidelines have been established for lung cancer screening,
such as the American Society of Clinical Oncology guidelines [31], the American Thoracic
Society [33], and the American Association for Thoracic Surgery recommendations [34]. In
2004, lung cancer screening was graded I (insufficient evidence to make recommendation) by the
U.S Preventive Services Task Force (USPSTF), because there was insufficient evidence that
screening by LDCT, chest x-ray or sputum cytology can decrease death rates [35]. Recently, the
USPSTF released another statement recommending annual screening with LDCT for high risk
15
individuals. Lung screening was graded B, meaning that there is moderate certainty that the net
benefit is moderate or substantial [36].
To enhance the effectiveness of LDCT screening in our communities, more efforts are needed to
increase public participation, by reducing health disparities and improving the quality of health
care services in underserved areas. Taplin et al. conducted a retrospective study to examine the
causes of late stage breast cancer diagnosis. Results from the study showed that women with low
income or less education had lower rates of screening and follow-up and were more likely to
have a diagnosis of late stage breast cancer than women with higher socioeconomic status [37].
Another study by Coughlin et al. indicates that women from ethnic minority groups, living in
poor areas, or had a lower number of office-based clinicians in their regions had higher odds of
being diagnosed with late stage breast cancer [38].
Educational programs that engage community members in raising awareness of benefits and
harms of cancer screening have been proven to increase public participation and decrease health
care disparities [39]. Following an evidence based protocol in screening is also an important
factor that determines the type and quality of the health care delivered. Many studies have shown
that a substantial number of primary care physicians don’t always follow the recommended
screening guidelines [40-42]. Implementing the National Prevention Strategy recommendations
of the National Prevention Council can ensure a high quality, equitable, and successful screening
program. These recommendations are based on four strategic directions: healthy and safe
community environments, empowered people, clinical and community preventive services, and
elimination of health disparities [43, 44].
16
In conclusion, the use of low dose computed tomography in lung cancer screening is a promising
public health intervention, which can have a huge impact on our communities. To establish a
nation-wide screening program many efforts are needed in different community and clinical
settings. First, public health professionals, researchers, and other stakeholders should pay more
attention to health disparities and educate the public about lung cancer screening; and second,
health care providers and medical institutions need to recognize the importance of standardized
imaging settings and lung nodule management protocols during their practice. A safe and high
quality screening program will help early detection of lung cancer, save more lives, and improve
the health and wellbeing of people.
17
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