Promising developments in lung cancer screening

Rachel E. Sanborn, M.D.
Co-medical director, Providence Thoracic Oncology Program
Medical oncologist, Providence Lung Cancer Clinic
Providence Oncology and Hematology Care Clinic-Eastside

Published July 2011

It is difficult to create a snapshot summary of an event as large as the American Society of Clinical Oncology annual meeting, which spanned five days in June and drew as many as 30,000 attendees from around the world.

The international conference highlights the latest advances in oncology research. As a thoracic oncologist, my focus is on lung cancer research.

The most pertinent news for primary physicians, pulmonologists, surgeons and oncologists came from the National Lung Screening Trial. The large, prospective, randomized study evaluated whether screening with low-dose CT scans would improve survival for people at high risk for developing lung cancer.

Until now there has been no evidence from a randomized trial that screening studies, such as chest X-ray or sputum cytology, provide a survival advantage over no screening.

The national study randomized 53,434 patients age 55 to 74 who had a history of smoking more than 30 packs a year. They received either annual low-dose screening CT scans for three consecutive years or yearly chest X-rays (the equivalent of a control arm) for the same period of time.

People with suspicious CT findings were followed based on a prescribed protocol. Depending on the level of concern, this could range from follow-up CT within a few months to referral for immediate diagnosis and intervention.

High yield also means more screenings

On initial CT scans, 27 percent of patients were identified to have suspicious findings, compared with 9 percent with chest X-ray. Nearly 650 patients were found to have lung cancer through CT (out of 18,149 scans), compared with 279 on the control arm.

According to a preliminary report released in the fall of 2010, the screening CT arm resulted in a 20 percent improvement in overall survival compared with the control arm. Overall, 320 patients needed to be screened to reduce one lung cancer death. Although that number sounds high, more than 460 patients need to be screened for breast cancer with mammography for the same outcome.

Lung cancer is now the leading cause of cancer-related death worldwide. The findings from the National Lung Screening Trial could have far-ranging implications and potential benefits.

Some major questions remain, however. How does this information translate to patients who were not included in the study, such as patients in different age groups, or those with a lesser tobacco history? Should CT screening stop after three years? Would ongoing CT scans provide a greater benefit? What will the societal cost be, as well as the psychological cost for the 17,500 patients whose abnormal findings turn out not to be cancer? How will we implement this in a broader population, and how will we engage patients as proactive partners in this endeavor?

Currently the U.S. Preventive Services Task Force is evaluating the data and awaiting cost analyses before making statements on the screening recommendations.

Clinical articles by Rachel E. Sanborn, M.D.