Tuesday, January 11, 2011
To Scan or Not To Scan for Early Lung Cancer
The National Cancer Institute funded this study that randomly allocated some 53,500 men and women at high risk (i.e., smoked about 1 pack or more cigarettes per day for 30 or more years) to either standard chest X-rays or low dose CT scans. Each person had a screening image taken annually for three years and were followed for an additional five years.
As of October, 2010, there were 649 cancers detected and 354 deaths in the CT group compared to 279 cancers and 442 lung cancer deaths in the X-ray group (obviously many of these latter cancer deaths were due to cancer NOT detected by the routine chest X-ray). The implication is that low dose CT scans detected cancer earlier resulting in successful therapy for many.
Lung cancer mortality per 100,000 was 246 and 308 for the CT group and the X-ray group respectively for a 20% reduction in lung cancer mortality.
But there are “buts” to the study. To save one life required 300 people to be screened. A CT scan costs at least $300 each, often much more. This means it cost $90,000 to save one life. Another “but” is CT screening detects lesions that are often not cancer. Indeed the false positive rate was about 25%. Since it requires a biopsy to prove it is benign, this adds not only risk and costs, but anxiety.
There is more information at http://tinyurl.com/2cutflw
The take away for now is that in high risk individuals, low dose CT scans can pick up early lung cancer. But the combination of high false positives and high costs weigh against its routine use even in these patients.
Praise for Dr Schimpff
The craft of science writing requires skills that are arguably the most underestimated and misunderstood in the media world. Dumbing down all too often gets mistaken for clarity. Showmanship frequently masks a poor presentation of scientific issues. Factoids are paraded in lieu of ideas. Answers are marketed at the expense of searching questions. By contrast, Steve Schimpff provides a fine combination of enlightenment and reading satisfaction. As a medical scientist he brings his readers encyclopedic knowledge of his subject. As a teacher and as a medical ambassador to other disciplines he's learned how to explain medical breakthroughs without unnecessary jargon. As an advisor to policymakers he's acquired the knack of cutting directly to the practical effects, showing how advances in medical science affect the big lifestyle and economic questions that concern us all. But Schimpff's greatest strength as a writer is that he's a physician through and through, caring above all for the person. His engaging conversational style, insights and fascinating treasury of cutting-edge information leave both lay readers and medical professionals turning his pages. In his hands the impact of new medical technologies and discoveries becomes an engrossing story about what lies ahead for us in the 21st century: as healthy people, as patients of all ages, as children, as parents, as taxpayers, as both consumers and providers of health services. There can be few greater stories than the adventure of what awaits our minds, bodies, budgets, lifespans and societies as new technologies change our world. Schimpff tells it with passion, vision, sweep, intelligence and an urgency that none of us can ignore.
-- N.J. Slabbert, science writer, co-author of Innovation, The Key to Prosperity: Technology & America's Role in the 21st Century Global Economy (with Aris Melissaratos, director of technology enterprise at the John Hopkins University).