Blood Test to Define Probability of Lung Nodule Being Cancer

[CindyA]

Blood Test to Define Probability of Lung Nodule Being Cancer? Could Help, but Potential to Backfire

November 25th, 2013 - by Dr. Jack West

One of the challenges of the increased frequency of chest CT scans being done for screening of people at higher risk of lung cancer, or done more commonly for chest symptoms, is that lung nodules are very commonly found, but most the time they aren’t cancer. Most studies show that >90% of lung nodules are benign, but the majority lead to additional work-up, and in nearly 100% of cases, they cause anxiety for the patient. What if a blood test could help clarify the probability that someone doesn’t have a lung cancer?

A recent paper from a highly respected group of researchers describes a new blood test called XPRESSYS that did a complex analysis of several hundred proteins to identity a 13-protein signature from a serum sample that assigns patients a favorable result associated with an extremely low probability of having lung cancer, so that a “negative” result was associated with a benign diagnosis 94% of the time. Importantly, a “positive”/”not negative” result was associated with only a 56% chance of the person having cancer, which is why the people developing the test that is now commercially available don’t consider a result other than negative helpful, and they don’t report it as a positive, but rather just negative or not.

Will this help? I must confess that I’m not confident it will. It’s a great idea — being able to use a blood test to help clarify whether someone should be reassured about one or more lung nodules not being cancer is wonderful. The problem is that the company says that a result other than negative should be ignored, but that’s far easier said than done. In reality, people won’t ignore a result that isn’t negative, and I suspect that patients and doctors who see a result that isn’t negative will escalate their anxiety and the pace of their workup even though only 50-60% of the people on the study who tested this way ended up having cancer.

In other words, while the concept is great, it seems to me that the results are helpful if the test is negative, but harmful if the test comes back as “not negative”, and you can’t just tell people to ignore results that make your test unhelpful.

What do you think? Would you NOT feel more anxious and want to move ahead faster with a workup if your test came back with a result other than negative?

http://expertblog.lungevity.org/