If Lung Cancer Screening Helps Some, Should We Screen Everyo

[NikoleV]

If Lung Cancer Screening Helps Some, Should We Screen Everyone? No, and Here’s Why Not

October 28th, 2012 - by Dr. Jack West

http://blog.lungevity.org/2012/10/28/lc ... t-not-all/

A post on About.com suggests that screening for lung cancer only the higher risk population of just those people 55-75 with a significant smoking history, as was done in the National Lung Cancer Screening Trial (NLST), would miss nearly 3 of 4 lung cancers. The implication from the argument in the piece is that broader screening across of a wider range of ages and smoking history is appropriate, since it should detect more lung cancer and improve outcomes. While it’s true that it can detect more cancers, that doesn’t mean that this is a good idea. Before I explain why, I’d like to emphasize that I am a proponent of lung cancer screening for an appropriate population and think it’s underutilized now. Nevertheless, It is categorically incorrect to presume that broadening screening to a wider population will lead to better outcomes. How can that be?

The NLST paper document a 20% improvement in overall survival in the screened population, who had a significant risk for lung cancer as defined by being old enough to have a greater probability of developing cancer, young enough to not have a high probability of competing risks limiting the ability to be treated for lung cancer, and enough of a smoking history that nodules found by screening would have a real probability of representing cancer vs. a benign finding like inflammation, infection, prior scarring, etc. Decades of studies on lung cancer screening have clearly illustrated that chest CT scans detects many nodules that are not cancer; this leads to additional scans, a significant risk of pursuing invasive tests to chase down findings, and very real anxiety in those affected. There may also be some potential risk from the radiation administered with scanning, which we want to be minimal, and which is undefined over the long term.

Screening for any cancer makes sense if you can focus on the people with a high enough risk that the benefit exceeds the risks. But there are risks, and not just the cost of doing CT scans tens of thousands of additional people every year (though that isn’t trivial). If screening is applied more broadly, to a group at low risk for actually having cancer, or not being fit enough to pursue treatment for a cancer detected early (such as a 79 year-old with significant heart disease), the beneficial effects of screening become diluted by the negative consequences that aren’t necessarily counterbalanced by a high enough upside from screening. The yield of screening will decline dramatically if it is applied to younger patients and never-smokers or those with a minimal smoking history. Here, there is likely to be a far greater probability that any suspicious findings will entail the repeat scans, interventions, and anxiety without sufficient probability that the findings will prove to actually be cancer.

So while more lung cancers could be detected if screening is pursued for a very broad population, the survival benefit would be diluted and could even lost in the face of a small but real risk from complications from invasive procedures or radiation over years and years of scans that aren’t demonstrated to improve survival in a younger or older population, or those with a minimal or no smoking history.

In clinical practice today, I see lung cancer screening being woefully underutilized today despite the evidence to support it. I believe this is because most primary care physicians and very possibly most insurers remain unconvinced that the benefit is really “worth it” for the cost of the intervention. I think that’s quite unfortunate, but diluting the benefit by screening a much lower risk population will only lead to greater skepticism. The evidence supports screening a population with a high enough risk of lung cancer…but screening more people isn’t necessarily better.