Published on July 27, 2018
How is lung cancer diagnosed? What tests will doctors need to perform before treatment? During this brief interview, noted lung cancer experts Dr. Edward Kim and Dr. Jeffrey Crawford discuss what diagnostic testing is used, recommended tests to evaluate clinical status throughout treatment, how the results are interpreted, and the purpose and value of lung tissue and liquid biopsies. They also explain what biomarkers health care teams are looking for before initiating therapy, how they are used to find a suitable treatment, and where these genetic insights are leading lung cancer research to next.
This is a Patient Empowerment Network program produced by Patient Power. We thank Celgene and Pfizer for their support.
Transcript | Expert Perspective: What Are Doctors Testing for in Lung Cancer Patients?
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Dr. Kim, let's talk about biopsy for a minute or how you get the information from the patient as to what's going on and then what to do about it, if you will. So getting a lung biopsy is not easy, and I know sometimes there's a problem getting enough tissue to do all the analysis you want, and now we've been hearing about more and more companies that are doing liquid biopsy. Okay.
So here's Mr. Jones, you want him to have a lung biopsy. Would there also be a liquid biopsy or—and not just at diagnosis but would you be doing some of this along the way to see if treatment is working?
Yeah, we've always been attracted to some of the other cancers that utilize liquid tests, ovarian cancer, CA125, PSA, prostate cancer, although we're still not really clear on where we're supposed to be using that to screen patients, but that has given people is principle that they like to follow things. And that's why cholesterol, for instance, was such a powerful sort of marker even though the relevance of it has been questioned by cardiologists. People can see there is an effect.
So, first of all, we have to say that nothing has completely replaced tissue. That is really the gold standard. It still is. I tell our interventionalists, whether it's a pulmonologist, interventional radiologist or anyone, I don't want a diagnosis. I want tissue. Because they can make a diagnosis by doing some brushings or some cytology, and they can tell me it's an adenocarcinoma favoring lung. That is not helpful. We need to absolutely have data that allows us to send for these molecular tests which includes, as Jeff mentioned, PD-L1.
We need EGFR mutation, ALK, ROS1, BRAF. These are all very important markers now that need to be sent. And in some cases, at some centers they send for the larger panels. What you get are 3- to 500 genes. I don't need 3- to 500 genes, but there are certainly clinical trials out there that can help match patients into trials based on these genes, so it is some utility.
But the blood-based markers and the biopsies are improving. There are definitely very—there are good data that show concordance when they're positive. So if you do a blood test and it shows a positive mutation for EGFR, for instance, you can be pretty confident that the tissue has that as well. The problem is that when you get a negative result. And the negative result, those percentages aren't disconcordant, because they really show the amount of accuracy, and so you can't take a negative test at face value. We don't standardly do liquid biopsies in patients unless the patient really has a contraindication to doing a traditional tissue biopsy.
As far as the surveillance aspect, as you mentioned, we do that on research. So on our research studies we do follow patients at every cycle with another blood draw, in addition to what they give in labs, so it's not an extra stick. It's just extra biopsy. And we do try to follow to see if we can see some of these different mutations either go up or down based on how the treatment is working or not working. And we're hopeful that this type of research down the road can lead to more predictive assays that are easier to gather so we can either surveil patients to see if they have cancer, if it's gone away, if it's come back.
You can imagine somebody who has been treated for cancer, who has no evidence of disease on a CAT scan but maybe with blood surveillance we can get an early sign if something is coming back. These are all possibilities and are being investigated, but right now it's really a backup plan if tissue can't be adequately gathered.
Dr. Crawford, of course you're doing research as well. Do you agree with this, where we are now and where we're headed?
Absolutely. I think what's happened in lung cancer is because of this need for tumor tissue, as Dr. Kim has pointed out, it's really transformed all the interventional things we've been doing. We were moving in the 90s to smaller and smaller biopsies, smaller and smaller needle aspirations just to make a diagnosis, but now we've gone back the other way where we're retraining our pulmonologists to get larger cores of tissues. They're developing new techniques to get more tissue, endobronchial biopsies. CT interventional people have been enormously helpful for getting core biopsies, so we get adequate tumor tissue to do the molecular tests we've been talking about.
So that's really fundamentally important and important to have at every institution hospital across the country. It's one thing for Levine or Duke to be able to do this, but it really needs to be done in smaller community hospitals and done well by interventional people who can get the tissue we need because the samples can always be tested at a central site if the pathology labs can't do it locally. We have to be able to get the tumor tissue.