Transcript Why screen for lung cancer?

Helical CT Screening for
Lung Cancer at Advanced
Radiology Consultants
Lung cancer missed on CXR
Why screen for lung cancer?
• Lung cancer is a major health problem
• It is the most common cause of cancer death
in men and women in the United States
• Approximately 160,400 patients will die as
a result of the disease over the course of the
next year
Why screen for lung cancer?
• Overall survival for lung cancer is presently very
poor- 5 year survival is about 15%
• Most patients present with advanced diseaseregional spread in 29% and distant spread in 52%
Advanced stage lung cancer at presentation
Why screen for lung cancer?
• Lung cancer prognosis depends on stage at
presentation
• Patients with Stage IA lesions (less than 3
cm in size and no lymph node or distant
metastases) have a 5 year survival of 67%
to 80%
• Therefore, want to identify patients with
early stage lung cancer in an attempt to
improve long term survival
Why screen for lung cancer?
• CXR screening is not recommended, but
physicians will order yearly CXR's on their
patients- particularly smokers or exsmokers
• A conservative estimate is that about 50%
of cancers will go undetected on the
patient's initial CXR
• Studies have demonstrated that helical CT is
clearly superior to CXR for the
identification of small pulmonary nodules
Small Lung Cancer Missed on CXR
Where is the cancer? Note small granuloma in left apex.
Lung Cancer Missed on CXR- Stage IIA
Cancer cannot be definitively seen on CXR even retrospectively
BIG Lung Cancer Missed on CXR- T4 lesion
Large cancer missed on CXR (luckily not by ARC physician)
Helical CT Screening Studies Summary
• Low dose helical CT is clearly superior to
CXR for the detection of early stage lung
cancer
• Between 60-90% of cancers detected on
low dose CT are Stage IA lesions
• CXR fails to detect a lesion in about 75% of
these patients
• Early detection of Stage I lung cancers will
lead to overall improved lung cancer
survival (I-ELCAP conclusion)
Positive lung screen CT scan
• Patient had screen in 2002, lost to follow-up
• Primary HCP sent patient for repeat screening
exam in 2007- positive for small lung cancer
2002
2007
Helical CT Screening the Controversy
• Survival ≠ Mortality
• Screening improves survival, but does
screening decrease mortality?
JAMA 2007; Bach PB, et al. Computed tomography
screening and lung cancer outcomes. 297: 953-961
• Screened patients were diagnosed with lung
cancer in far greater numbers than would have
occurred in the absence of screening and the
majority (67%) were stage I or stage II
• However, there was no decrease in overall
mortality based upon “predicted models”
Bach PB, et al. Limitations
• Lacked non-screened comparison group
• Mortality “estimates” used in the study
depend on the validity of prior risk factor
analyses- these may not be applicable
• Because of the small number of patients in
the Bach study, the 95% confidence interval
for their data might allow for a lung cancer
mortality reduction as large as 30%
• Therefore- no conclusive data regarding
mortality yet published
Survival and Mortality
• Other screening exams have not been
shown to have effect on mortality
• Although in widespread use, prostate cancer
screening is not yet validated as providing a
clear benefit in terms of reducing mortality
from prostate cancer
Helical CT Screening Limitations
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Missed cancers
False positives- non-calcified granulomas
Interval cancers between scans
Radiation
Helical CT Screening Limitations
• Lung cancers will be missed- up to 50% of
cancers will not be detected on the patient’s
initial screening exam
• Highlights need for patient follow-up
• Good news is missed lesions are less than 1
cm and typically ground-glass in character
(bronchoalveolar cell carcinoma)
Helical CT Screening Limitations
• Lesions that are missed on initial screening
will be detected on follow-up exams and are
generally Stage I
• NOTE: CXR detects none of these lesions
Missed Cancer on Screening CT
1993
1995
Bronchoalveolar cell cancer
Helical CT Screening Study Limitations
• False positives- non-calcified nodules are detected
in a large number of screened patients, but only
about 1-2% of these nodules prove to be malignant
• CT cannot achieve perfect discriminatory
performance- cannot 100% reliably conclude a
lesion is malignant based upon it’s appearance
• Small nodules require follow-up and this can lead
to patient anxiety
Helical CT Screening Study Limitations
• A negative screen does not preclude the subsequent
development of lung cancer, even between scans- although
a rare occurrence
Highly advanced lung cancer developed over only 10 months
Helical CT Screening Limitations
• Scan involves use of radiation
• ARC uses a low dose technique
• Radiation exposure is approximately 10
times higher than a CXR, but is only onesixth that of a conventional CT
• Remember- scan provides about 10 times
the information of a standard CXR
Screening for lung cancer- The challenge
• KEY TO SUCCESSFUL SCREENING:
Must identify the proper subset of patients
that will most benefit from screening
• Best candidates are smokers (present or ex)
with 20 pack year smoking histories
• We are happy to discuss the scan with you
or any patient that expresses an interest in
lung cancer screening
Why we need to screen
Where is the cancer?
Why we need to screen
Stage IA cancer that cannot be seen on CXR
Why we need to screen for lung cancer
The annual number of deaths from lung cancer is greater than the
numbers of deaths from breast, colon, and prostate cancer combined
200000
180000
160000
140000
120000
100000
80000
60000
40000
20000
0
New cases
Deaths
Lung
Breast
Prostate
Colon