Effective clinical strategies are needed to combat lung cancer, the leading cause of both cancer incidence and cancer death.

Advances in CT technology now permit imaging at sufficient resolution to identify lung nodules as small as a few millimeters in diameter while exposing patients to lower doses of radiation than would be required for a conventional thoracic CT scan. The largest and most prominent study to date of CT-based screening for lung cancer, the International Early Lung Cancer Action Program (I-ELCAP), has reported that screening with low-dose CT can successfully identify curable lung cancer at an early stage. The I-ELCAP protocol involved screening at baseline and annually thereafter. New nodules identified were investigated within a defined algorithm incorporating frequent CT scans, positron emission tomography scans, antibiotics or lung biopsy.

First, screening brings with it important unintended consequences. In the I-ELCAP study, screening was inefficient, identifying cancers in only 1.3% of participants. The need to find cancers when they are small, although seemingly important, does not match the biology of all tumors. Rather than identifying cancers for which the potential for cure would otherwise have been missed, screening may merely provide earlier identification of cancers that remain curable after becoming clinically apparent (lead-time bias). Clinicians ought to know better than to leap too early on the cancer screening bandwagon. Prostate-specific antigen testing is widespread in clinical practice, yet it has never been proven to reduce mortality from prostate cancer. Although a beneficial effect of mammography has been proven in older women, whether it reduces mortality from breast cancer in women aged 40–49 years is unknown.

National and international professional organizations representing cancer, lung disease and medical imaging specialists could help by collaborating on joint policy statements to guide practice in the interim. Until then, if clinicians choose to offer CT screening for lung cancer, such decisions should be based on their best judgment of the incomplete evidence available and on the values and preferences of their patients, with forthright acknowledgement of the present uncertainty. Ideally, such patients should be enrolled in clinical trials of CT screening. Similarly, policy-makers should wait for better evidence of efficacy and cost-effectiveness before investing in more capacity for CT screening programs. In the meantime, given how much we know about the prevention of lung cancer, targeting smoking avoidance and cessation, rather than detection and management of lung cancer, would seem a better investment.

(Source: Canadian Medical Association )

TrackBack URI for this entry

Comments (0)

Subscribe to this comment's feed