Published on December 20, 2016
How can a single biopsy accurately profile a tumor targeted for therapy? Isn’t it necessary to do multiple biopsies over time? Dr. Ross Camidge of the University of Colorado-Denver, and Dr. Nisha Mohindra of Robert H. Lurie Comprehensive Cancer Center answer this Ask the Expert question. Dr. Camidge points out that while the dominant mutation stays the same and only requires one biopsy to determine that mutation, multiple biopsies keeps up with the evolution of the cancer. Dr. Mohindra adds that targeted therapy alters the tumor and follow-up biopsies indicate those changes.
Transcript | Can a Single Biopsy Accurately Profile My Lung Cancer Tumor?
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I have another question from online. A patient says, “I’m uncertain as to how a single biopsy can accurately profile a tumor for targeted therapy. Wouldn’t it be necessary to do multiple biopsies over time?” Ross, I’m going to hit you first.
Yes and no. Not yes and no can you hitme first. Of course you can hit me first.
No, in the sense that many of the things which determine somebody’s immediate response to therapy—like it happened very early in the development of the cancer. We call these driver abnormalities. They’re really what sets the cancer off and going. So they’re present in almost every cell in the cancer. People have also used analogies about tree trunks. So they’re in the trunk. They’re not just in the branches. So if you cut them down, the whole tree falls down. You don’t just trim off a branch.
The reason why the answer’s yes is because of what was touched on earlier—is the cancer will evolve in response to a specific environment. So although that dominant mutation may stay the same, additional mutations which alter how it’s behaving can occur later.
Also a tumor may have more than one type of lung cancer in it. So a treatment might be effective on one part of the cancer, and not test another which is why we’re talking about combination therapies, correct?
Yes. So when I have a patient on a targeted therapy and tumor changes, either it grows or stops responding, I do want another biopsy to know what else is going on, just as Ross said. And then if a tumor is truly acting different than I would expect for the type of tumor it is, I biopsy to make sure that sometimes you do have a mixed histology. And the non-small cell part was treated, and now there’s a small cell. So I think biopsies cancer help in the right clinical context, and re-biopsies are often needed to know more.
One of the nice things that happened in recent years was changing the way we think. So these guys are surgeons, and the radiation oncologists, they used to get their major work dealing with early stage disease. But now as we’ve gotten good at controlling most of the disease, and then a little bit of the biology changes and only a little bit of the cancer might become active,you can create a new concept of an early stage of progression, what we call oligo-progressive disease.
And that I think has really reinvented the role of bringing in local therapies, even into the stage IV setting.