It’s been a disappointing month for proponents of screening.
You remember what screening is? Screening is testing someone for a disease who does not have any signs or symptoms of that disease. In general it means testing a wide population for a specific disease. So if I have a chronic bloody cough and unintentional weight loss, my doctor isn’t screening me for lung cancer. He’s doing tests to diagnose or rule out lung cancer because I have suggestive symptoms for that disease. Got it?
Lung cancer has long been the number one cancer killer in the US. So a screening test that would help save lives from lung cancer is much in demand. In the 1970s studies tested screening for lung cancer with annual chest X-rays. The trials did not find any benefit.
Apparently those 1970s studies had some procedural flaws that made them unconvincing. And X-ray technology has improved in the last 30 years. So it was conceivable that chest X-rays got a bum rap and were actually a valuable screening tool. This prompted the National Cancer Institute to retest chest X-ray screening as part of its Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO) which is a large clinical trial testing various cancer screening tests.
The results of the lung cancer portion of this trial were published in this week in the Journal of the American Medical Association. Over 154,000 people were randomized to either receiving annual chest X-rays or to usual care by their physicians. There was no difference between the two groups in deaths from lung cancer.
So that settles a question I thought was already settled. Healthy people don’t benefit from periodic screening chest X-rays.
This finding comes on the heels of other negative news about screening. The ovarian cancer branch of PLCO has also demonstrated that the blood test CA125 is not valuable for ovarian cancer screening. And just two weeks ago the US Preventive Healthcare Task Force’s recommended against PSA screening for prostate cancer.
For lung cancer, there is some hope, however. A study in July showed that in a selected population of high-risk smokers screening with spiral CT scans saved lives.
Avoiding unproven tests isn’t just a matter of avoiding expense. Unproven tests (or tests proven not to help) cause more harm than good by leading to other invasive unnecessary tests. The informed patient doesn’t want to be screened for “everything”. He wants only what has been proven to help.
Looking For Lung Cancer With A Yearly X-Ray Doesn’t Reduce Deaths (Shots, NPR’s Health Blog)
X-Rays No Help Against Lung Cancer (Wall Street Journal)
Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (National Cancer Institute clinical trial page)
Screening by Chest Radiograph and Lung Cancer Mortality (Journal of the American Medical Association)
Spiral CT Scans Save Lives from Lung Cancer (my post about lung cancer screening with CTs)