Treatment-Related Interstitial Lung Disease - Episode 14
Experts discuss the optimal monitoring of patients to identify interstitial lung disease early and how to intervene.
Joyce A. O’Shaughnessy, MD: Let’s talk about monitoring for ILD [interstitial lung disease]. Is anything recommended? Is anything proven? Mark, how do you approach that?
Mark D. Pegram, MD: I mentioned the simple history and physical findings, but most often we see these changes radiographically since we’re doing repeated staging with CT imaging frequently in the cases of metastatic cancers. However, for early stage disease that’s not the case. I’m more concerned with the prospect of using some of these drugs in the neoadjuvant or adjuvant setting where we may not be doing serial thoracic imaging on a regular basis. That’s a whole different problem to have to worry about for the future, but for the time being, we often encounter this simply with CT imaging. When I’m using drugs that can be associated with ILD, I try to keep my restaging scans on schedule. During the COVID-19 pandemic, we’ve been kind of stretching out staging in some selected patients if they’re on endocrine therapy alone, for example, or if they’re doing well for many months or even years in some cases. We tend to stretch those out so that we reduce the risk of patients coming into the center and being exposed to the virus. But for these types of drugs, trastuzumab deruxtecan, the CDK4/6 inhibitors, it’s important to keep on schedule with serial restaging in metastatic cancers in order to screen for this condition because early intervention seems to be the key.
The other thing is the differences between CT scan and PET [positron emission tomography] CT; my understanding is that PET CT has fewer cuts through the thorax compared to ordinary thoracic CT. The best imaging for this condition once you make the diagnosis and you’re following it serially is actually a high-resolution CT, which has even finer cuts. That’s probably the most accurate way to follow the resolution radiographically. Resolution of clinical symptoms and signs is also very important. I want to ask Charles about any other tests. I know you can measure things like the diffusion capacity of carbon monoxide, for example. PFTs [pulmonary function tests] sometimes show a restrictive defect, but unless you get baseline PFTs how would you know how to interpret this if you just get it on the fly? I’m curious to know what Charles has to say about that situation.
Charles A. Powell, MD, MBA: The points you raise are terrific. I enjoyed the point about how most of what we know right now is in the advanced cancer setting, and the challenges will be to apply these learnings to the early cancer setting for neoadjuvant or adjuvant use where the imaging cadence will be different. I agree, that’s a big challenge. I don’t know if we have any answers for that yet, but we are learning in the advanced cancer stage. As far as the cadence of imaging goes, the most important imaging study is the baseline study. That is what is going to tell us whether there is interval change and what the temporal onset of that interval change is in relationship to the exposure to the implicated drug. That’s crucially important. For patients who are being treated with a drug that may be associated with lung toxicity, it’s crucially important to have that baseline scan before initiation of treatment whenever possible.
The other really important point, as you mentioned, is educating the patients about the importance of their symptoms. There are many instances where patients may present with advanced drug-related pneumonitis, and then we learn that the symptoms have been going on for a long time. Rather than waiting for the imaging to show a progressive case, having a case brought to attention earlier because of the patient’s symptoms would be very useful. That education is important for the patients and also for their providers, and we all understand that these treatments are incredibly important to the patients and to the providers. However, it is crucial that the treatments be done in a safe fashion and being aware of a change in symptoms and allowing opportunity to perform the evaluation to determine the best course of action to mitigate toxicity to allow the benefits of treatment is really important.
As far as lung function testing goes, I agree that can be important too. Restrictive lung disease, which is a reduction in lung volume, that typically happens late, and that would almost certainly happen after the patient had symptoms and profound radiographic abnormalities in many cases. There are earlier changes that we can see in lung function. The diffusion capacity typically isn’t used in screening but helps us to understand the severity that may be associated with symptoms and/or radiographic abnormalities. I would lay my hands on symptoms and imaging. We have pulmonary function testing, and there’s also some opportunity to explore some home monitoring with pulse oximetry to measure oxygen levels. Not so much at rest because again that happens late if there’s a change, but change in oxygen levels measured by pulse oximetry during some type of exercise may be a useful strategy.
Joyce A. O’Shaughnessy, MD: Interesting, so that can be subtle. Even in the clinic if you had patients, let’s say in the adjuvant setting, for example, where you have patients on agents that have some risk. You could have them walk around the clinic and then do a pulse oximetry. It’s more subtle. That happens a little earlier as opposed to at rest, which is a later finding.
Charles A. Powell, MD, MBA: We do that routinely in the clinic. We’re walking up and down with our patients who may have or do have interstitial lung disease.
Joyce A. O’Shaughnessy, MD: Interesting.
Transcript edited for clarity.