Learning How and Why Lung Cancer Patients First Get Diagnosed

Researchers are looking into the widespread implementation of computed tomography (CT) scanning for the early detection of lung cancer in a public heath environment, trying to determine two key problems: without screening, why and how do patients with lung cancer get diagnosed with the disease at first and what percentage of these cases would be identified by screening efforts?

Dr. David Gerber, an oncologist and assistant professor of internal medicine at the University of Texas (UT) Southwestern Medical Center (Dallas, USA), has used the electronic medical records (EMRs) data of more than 400 patients in a single-center study that is further exploring results from the US National Lung Screening Trial (NLST) released in 2010. The NLST already showed a reduction in lung cancer mortality may result in widespread CT-based screening of select populations. This population was strictly defined according to age (55 to 74 years) and smoking history (at least 30 years of one-pack-a-day smoking).

Dr. Gerber and his coworkers, in a study published January 3, 2013, in PLoS ONE--the Public Library of Science’s online journal, reviewed the records of patients who were diagnosed with stage 1 or stage 2 non-small-cell lung cancer over a recent 10-year period, and found that the proportion of cases identified by CT scan (without an earlier chest radiograph) increased nearly 50% during this period. Simultaneously, the percentage of patients who underwent initial chest imaging to evaluate symptoms declined more than 30%. Finally, the researchers found that only half of early-stage lung cancer cases would meet NLST criteria for lung cancer screening.

“Our results suggest that a substantial proportion of patients currently presenting with early-stage lung cancer would continue to do so independently of radiographic screening if such a program were implemented according to NLST criteria,” Dr. Gerber said. “The possibility of frequent detection of early-stage disease outside of a screening context seems more likely with lung cancer than with other malignancies, as chest imaging is a more common practice in nonscreening clinical care than are mammograms, Pap smears, and colonoscopies.”

Whether radiographic screening for lung cancer should be extended to a wider population is not yet known. “Adhering to specific guidelines may be challenging for clinicians,” Dr. Gerber said. “For instance, in our sample, almost 25% of patients with early-stage disease would be ineligible for screening because they are too old under NLST criteria.”

Dr. Gerber noted that specific professional organizations, such as the National Comprehensive Cancer Network, have neglected a maximum age cut-off from their screening recommendations. “Until there is sufficient evidence to offer screening to a broader population,” Dr. Gerber said, “clinicians should remain aware of the diverse reasons for and circumstances of early-stage lung cancer presentation to expedite further evaluation and potentially curative treatment.”

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University of Texas Southwestern Medical Center