Helical CT Screening for Lung Cancer at Advanced Radiology Consultants

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Helical CT Screening forLung Cancer at Advanced
Radiology Consultants
Lung cancer missed on CXR
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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

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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 disease-
  regional spread in 29 and distant spread in 52

Advanced stage lung cancer at presentation
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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

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Why screen for lung cancer?

• CXR screening is not recommended, but physicians
  will order yearly CXR's on their patients-
  particularly smokers or ex-smokers
• 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

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Small Lung Cancer Missed on CXR
Where is the cancer? Note small granuloma in left
apex.
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Lung Cancer Missed on CXR- Stage IIA
Cancer cannot be definitively seen on CXR even
retrospectively
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BIG Lung Cancer Missed on CXR- T4 lesion
Large cancer missed on CXR (luckily not by ARC
physician)
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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)

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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
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Helical CT Screening the Controversy

• Survival ? Mortality
• Screening improves survival, but does screening
  decrease mortality?

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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

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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

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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

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Helical CT Screening Limitations

• Missed cancers
• False positives- non-calcified granulomas
• Interval cancers between scans
• Radiation

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Helical CT Screening Limitations

• Lung cancers will be missed- up to 50 of cancers
  will not be detected on the patients 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)

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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

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Missed Cancer on Screening CT
1993
1995
Bronchoalveolar cell cancer
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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 its appearance
• Small nodules require follow-up and this can lead
  to patient anxiety

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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
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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 one-sixth that of
  a conventional CT
• Remember- scan provides about 10 times the
  information of a standard CXR

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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

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Why we need to screen
Where is the cancer?
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Why we need to screen
Stage IA cancer that cannot be seen on CXR
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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