Helical CT Screening forHelical CT Screening forLung Cancer at Advanced Lung Cancer at Advanced

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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 disease- regional 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 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

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

• 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 one-sixth 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

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Lung Breast Prostate Colon

New casesDeaths

The annual number of deaths from lung cancer is greater than thenumbers of deaths from breast, colon, and prostate cancer combined