Monday, 19 August 2013

A Case In Favor Of Lung Cancer Screening Is Emerging

John Gever has reported for MedPage Today "Lung Cancer Screening Wins More Support." A researcher has said consensus is starting to build that long-time smokers should have annual CT-based screenings to reduce lung cancer mortality. A series of studies has suggested a mortality reduction in high-risk current and former smokers who underwent screening along with last year's report from the National Lung Screening Trial (NLST) has built a case in favor of screening for lung cancer, although this is still officially discouraged in primary care.

The researcher says that a forthcoming joint evidence review by several organizations, including the American College of Chest Physicians, the American Society of Clinical Oncology, the National Comprehensive Cancer Network (NCCN), and the American Cancer Society, had determined that screening in high-risk patients has value. According to James Jett, MD, their report is anticipated to include the following statement, "We conclude that low-dose CT screening may benefit individuals at an elevated risk for lung cancer but uncertainty exists about potential harm and generalizability of the results."

Last November The NCCN had issued a less qualified endorsement of CT-based screening for high-risk individuals after findings of a 20% reduction in lung cancer mortality and a 6.7% reduction in all-cause mortality associated with screening. This report said such individuals should be screened, but only after discussing the risks, primarily the high likelihood of false-positive results and the unnecessary procedures that may follow, with their physicians.

"High-risk" are defined as patients age 55 to 74 with a smoking history of at least 30 pack-years and who had smoked within the previous 15 years; or a patient who is 50 years and older with a smoking history of at least 20 pack-years and another risk factor other than second-hand smoke exposure. Other risk factors are primarily occupational exposures to lung carcinogens such as asbestos.

Jett has said lung cancer "isn't just a cancer problem. It's the cancer problem." However, there is a lack of a technology with acceptable sensitivity and specificity for this screening. Chest x-rays can easily miss early-stage tumors which are near other structures and they cannot distinguish malignant tumors from benign uncalcified nodules. And although low-dose CT scans provide much greater resolution and have improved the sensitivity substantially, the specificity problem remains.

Furthermore, aside from false positives the risks from such screening remains uncertain, including those of radiation exposure as well as from possibly unnecessary treatment which may result from screening. And a practical barrier to screening is that annual CT scans are relatively expensive and most insurers do not cover them at this time. And so the jury is still out on the question of lung cancer screening.

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