Editorial
Should We Expand Eligibility for Low-Dose CT Scans?
Jeffrey N Tarascio1*, Sam W Fox1 and Francine Jacobson2
1Division of Thoracic Surgery, Brigham and Women’s Hospital
2Division of Radiology, Brigham and Women’s Hospital
*Corresponding author: Jeffrey N Tarascio, Department of Thoracic Surgery, Brigham and Women’s Hospital, USA
Published: 18 Sep, 2018
Cite this article as: Tarascio JN, Fox SW, Jacobson F.
Should We Expand Eligibility for Low-
Dose CT Scans?. Clin Surg. 2018; 3:
2109.
Editorial
Lung cancer is the deadliest and the most preventable cancer related death. Each year, the North
American Association of Central Cancer Registries (NAACCR) annual report releases the trends for
the most common cancers in the United States. From 2011-2015, lung cancers remained the leading
cause of cancer related deaths in men and women and accounted for an estimated 1,690,000 deaths
globally in 2015 alone [1,2]. In the most recent NAACCR report, the five-year survival rate for Stage
I lung cancer (which includes lung and bronchus cancer) was 55.1%. If diagnosed at Stage IV, the
survival rate dropped to 4.2%. The most troubling statistic is that only 20.7% of cases were diagnosed
at Stage I, while 43.6% were diagnosed at the more fatal Stage IV [1].
Even with a significant decrease in smoking, lung cancer has maintained the second highest
incidence rate of all cancer diagnoses [1]. The current screening guidelines issued by multiple
organizations including The American Cancer Society (ACS), The National Comprehensive
Cancer Network (NCCN), and The American Association for Thoracic Surgery’s (AATS) follow
the parameters of the National Lung Screening Trial (NLST), and are most relevant for individuals
at high risk for lung cancer due to cigarette smoking. While the correlation between smoking and
cancer is undoubtedly the single greatest determinant in developing cancer, this familiarity heuristic
towards tobacco may be blindsiding us. Current studies show that the etiology of nearly 25% of lung
cancers are not attributed to smoking and further studies show that lung cancers in never-smokers
(individuals who have smoked less than 100 cigarettes in their lifetime) are the 7th most common
malignancy worldwide [3-5]. Given this prevalence, it may be necessary to include other variables
in addition to tobacco related risks in future guidelines.
The ACS screening guidelines are based upon the NLST data. The findings of NLST were
conclusive; annual Low-Dose Computed Tomography (LDCT) screenings reduced lung cancer
specific mortality by more than 20% [6]. However, the NLST inclusion criteria (and therefore current
ACS screening guidelines), only opened the study to those between 55 and 74 years old, those with
a history of at least 30-pack years, and former smokers who had quit within the last 15 years [7].
The NCCN has established two high-risk groups, one that is identical to the ACS guidelines, and
a second high-risk group that contains people 50 years and over with 20-pack years or more of
cigarette smoking, and have at least one additional risk factor (other than second-hand smoke) [8].
The AATS guidelines expand the screening opportunity of the NCCN by increasing the screening
age through the eighth decade of life, and recommend continuation of screening beyond 15 years
of smoking abstinence [9]. While both the NCCN and AATS recommendations have included
additional risk factors for screening, their guidelines are still predominantly based on tobacco use.
The United States Preventive Services Task Force’s (USPSTF) recommendation (also based
on the NLST trial) requires commercial insurance coverage for individuals between 55-80 with a
minimum 30 pack-year history of cigarette smoking and that the individual has smoked within the
preceding 15 years [10]. For those covered by Medicare and Medicaid, the Centers for Medicare and
Medicaid Services (CMS) somewhat reluctantly agreed to recommend lung cancer screening CT for
individuals between 55 and 77 who meet smoking history requirements (30 pack-years) [10]. CMS
eligibility also includes provisions to add lung cancer screening counseling and a shared decision
making (the use of a qualified individual who can outline the risks and benefits of screening) before
enrollment in a LDCT screening program. Additionally, CMS requires inclusion in an approved
clinical registry that contains reporting from all lung cancer CT scans, not just Medicare beneficiaries
[10].
Additional analyses of the NLST data by Pinksky et al. [11] highlighted demographic differences
between subpopulations including evidence that women and underserved minorities develop
lung cancer at a younger age and with less smoking intensity. The incidence of lung cancers being diagnosed in very young, particularly women never-smokers, has
been observed in increasing frequency and additional studies of
early onset lung cancer is being performed [12,13]. NAACCR data
was used to show a slightly higher incidence rate among women
non-smokers than non-smoking men, and a complete reversal in the
overall lung cancer incidence rates in women compared to men [13].
Across multiple ethnic groups, age groups and smoking histories,
women are being diagnosed with lung cancer at a higher rate than
men [13]. Nearly 25% of all lung cancer cases worldwide, and in 53%
of women who develop lung cancer, tobacco smoking is not directly
attributed as the cause [3]. It is clear that critical risk factors unrelated
to tobacco are being missed and that current guidelines are excluding
individuals that need to be screened.
Collection of data for younger adults through the required
clinical registry reporting is limited due to the lack of insurance
coverage for screening. Such cases are no longer anecdotal and we
do not adequately understand increasingly important non-tobacco
risk factors. Some are genetic, such as individuals carrying inherited
EGFR gene mutations called T790M [12]. This underlies at least
part of the significance of family history of early onset lung cancer,
i.e. those before age 60. To date, this risk factor has been identified
and studied in lung cancer patients. Prospective identification of
T790M remains limited but it does highlight the potential to identify
increasingly specific risk factors that, in combination, would be as
powerful for selection of high risk individuals for screening to further
reduce lung cancer mortality [12]. As we identify new risk factors, it is
also important to recognize shortcomings to screen individuals who
are eligible even under the current guidelines.
Lung cancer screening penetration in populations that meet
current guidelines is very low. Su et al. [14] studied lung cancer
screening in an underserved population with insured patients and
found that only 33 out of 175 eligible participants who had established
a relationship with a PCP and were eligible for screening based on
the USPSTF guidelines, went on to receive LDCT screenings that
preceded their diagnosis of lung cancer. This study was completed in a
major metropolitan screening center in the Northeast, and we believe
that it is fair to consider that the screening penetration is less than
10% in populations with lower rates of insurance. It is with certainty
that there are discrepancies and biases to those who are getting sent,
and followed up on, for lung cancer screening. Survival is significantly
decreased for those that did not receive early screening [1]. This poses
a risk for those that are underserved, vulnerable, and have low health
competency. Barriers to care such as poor access, time constraints,
language discordance, and socioeconomic factors could be limiting
the success of screening this population [14]. Underserved vulnerable
populations require greater education and supportive services such as
smoking cessation programs.
One possible supplement to the future of lung cancer screening
guidelines includes the use of lung cancer risk prediction models.
Accounting for and analyzing an individual’s personal factors
including: familial history of cancer, environmental/occupational
exposures, previous lung conditions and potentially clinically
collected data, could help identify smokers and non-smokers who are
at high risk while lowering downstream costs. Some of these models
have already identified these potential risk factors. Gray et al. [15]
preformed a systematic review of lung cancer prediction models and
found that there are currently 25 distinct models for determining
an individual’s risk of developing lung cancer. Some of the
epidemiological models have been extensively validated, including
the Liverpool Lung Project (LLP) and the Prostate, Colorectal and
Ovarian (PLCO) Cancer Screening Trial. Between these two trials,
a total of 10 non-smoking risk factors where included as variables.
These risk factors fell under the categories of personal factors such
as family history of cancer, environmental/occupational exposures
and previous lung conditions. Other epidemiological plus clinical
assessment models went on to include clinically collected variables
such as the presence of a single nucleotide polymorphism, Body Mass
Index (BMI), physical activity, and fasting glucose. Most notably,
“the (PLCOM2012) model had a better prediction rules performance
than the NLST, so applying this model…could offer an improvement
in selective screening trials” [16]. After further studies and careful
validation, the use of these prediction models could provide a costeffective
method for patients and physicians to determine who should
begin annual LDCT screenings.
Seven years after the results of the NLST were reported, lung
cancer continues to be the deadliest cancer worldwide. This begs
the question if we need to improve screening education and
recruitment, expand to a larger cohort using newer techniques such
as mathematical modeling, or both. Annual LCDT screening has been
a great first step to improving survival, but when 43.6% of individuals
still being diagnosed with late stage disease, our current policies are
not sufficient. We need to increase smoking cessation programs,
raise awareness about annual lung cancer screenings, and conduct
further studies to concretely identity the potential risk factors that are
contributing to disease in non-smokers. In addition, we need to study
and eliminate the screening guideline disparities which benefit older
heavy smokers and ignore women and minorities who get cancer
with less smoking and at a younger age.
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