Dec 282012

The American College of Chest Physicians (ACCP) has issued its long-awaited recommendations on lung cancer screening with chest CT -- and far from a ringing endorsement of screening, they are conservative and subdued, emphasizing the potential risks of an uncontrolled approach to lung cancer screening in the general population.

The American Society of Clinical Oncology (ASCO) joined ACCP in the statement, and the American Thoracic Society (ATS) endorsed it, issued in the June 13 2012 JAMA and published online as a practice guideline. (See alsoAmerican Lung Association endorses CT screening for lung cancer.)

ACCP Recommends Lung Cancer Screening "Be Offered" Only to High-Risk Patients

ACCP & ASCO only weakly recommend (Grade 2B) that people at high risk (i.e., meeting the National Lung Screening Trial entry criteria, age 55-74 with >30 pack-year history, quit <15 yrs ago or still smoking) "be offered" annual screening with low dose CT -- and only at centers that can deliver a comparable level of comprehensive care that was available to participants in the NLST.

ACCP & ASCO advise people not meeting the NLST criteria NOT undergo lung cancer screening with low-dose CT (Grade 2C). This includes people at lower risk for cancer or who have a shorter life expectancy (e.g., <30 pack-years, younger than 55, older than 74, or quit smoking >15 years ago).

What does "comprehensive care" mean? They remark in the article:

Screening should be conducted in a center similar to those where the NLST was conducted, with multidisciplinary coordinated care and a comprehensive process for screening, image interpretation, management of findings, and evaluation and treatment of potential cancers.

In other words,they weakly recommend that if multidisciplinary care integrated with a well-organized screening process is not available, lung cancer screening should not be performed, even in high-risk people meeting NLST entry criteria.

Advisory Groups' Recommendations Differ: An Expertocracy Divided

In the wake of the positive findings of the National Lung Screening Trial (NLST) -- which showed that annual low-dose chest CT scans can prevent deaths from lung cancer -- experts and their advisory panels have been unsure how strongly to endorse lung cancer screening with CT.

The ACCP/ASCO statement, endorsed by ATS, are more cautious than the recent recommendations by the American Lung Association, which advised high-risk current and former smokers meeting NLST criteria to get CT screening (not just that it "be offered"). The ALA's recommendation also did not advise lower-risk people not to get lung cancer screening, and barely mentioned the risks of screening in its online advice to patients.

Since low-dose CT scanning reduced the risk of dying from lung cancer in heavy smokers by ~20%, why not make it national health policy? There are numerous concerns with such an approach:

  • The absolute risk reduction was only 0.33% -- meaning 320 high-risk people needed to be screened to save one life.
  • Lung cancer screening detects abnormalities in up to 40% of screened patients; 95% of the abnormal findings are not cancer (false positives), but can lead to harmful interventions in otherwise healthy people (needles, surgeries, etc).
  • If lung cancer CT screening is provided to groups of people at lower risk (e.g., lighter smokers, or otherwise not meeting the criteria of the NLST), the potential benefits would be expected to fall (i.e., more people would have to be screened to find each curable lung cancer), and possibly resulting in more harm created than lives saved.

The story of prostate cancer screening with PSA has made clear that doctors and patients in the community don't pay much attention to expert guidelines for cancer screening, anyway -- at least, not when the guidelines recommend against screening. The decision to get screened for cancer is intensely individualized, influenced by culture, personal values and experiences, media messages, and hopes and fears (both the patient's, and her physician's). When expert societies' recommendations differ, you can expect that patients will consider them even less highly in their personal decision-making.

Bach PB et al. Benefits and Harms of CT Screening for Lung CancerA Systematic Review. JAMA 2012;307:2418-2429.  

See also: American Lung Association endorses CT screening for lung cancer

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ACCP, ATS only weakly recommend lung cancer CT screening, warn of harms