Lung Cancer: Radiological Diagnosis (Part 1)

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Lung Cancer: Radiological Diagnosis (Part 1)




Guest:  Dr. James Ravenel – Radiology

Host:  Dr. Linda Austin – Psychiatry


Dr. Linda Austin:  I’m Dr. Linda Austin.  I’m talking, today, with Dr. James Ravenel who is Associate Professor of Radiology here at the Medical University of South Carolina.  He is also a specialist in the area of thoracic imaging, which is the study of the lungs and chest by using radiographic images.  Dr. Ravenel, let’s talk, in this podcast, about using x-rays and other techniques to screen for lung cancer.  Lung cancer is, indeed, a very common form of cancer, is it not?


Dr. James Ravenel:  It is one of the more common cancer diagnoses and it is the leading killer of men and women in terms of cancer deaths.  It outstrips breast, colon, prostate and ovarian deaths combined. 


Dr. Linda Austin:  Why might it be more serious than some other forms of cancer, such as breast cancer?


Dr. James Ravenel:  Unfortunately, by the time we detect most lung cancers, they have spread beyond the lung.  They’ve spread either to the mediastinum, which is the area around the heart, trachea and lymph nodes, or outside of the chest, to liver, the adrenal gland, perhaps bones, or even to the brain.  At that point, we cannot surgically resect the tumor.


Dr. Linda Austin:  Now, why is it that it will often have spread without the person really knowing it?  What are some of the earliest symptoms of lung cancer that may be confusing to a potential patient?


Dr. James Ravenel:  Unfortunately, many of the symptoms of early lung cancer are the same as they may have with their bronchitis or asthma or other respiratory disorders.  So, they may a cough that doesn’t go away.  They may be producing a fair amount of sputum.  They may see a little bit of blood-tinged sputum.  But none of these are specific for the diagnosis of lung cancer, so they make think it’s just their normal cough and cold symptoms.  More serious symptoms, such as personality changes because the tumor is in the brain or because they have pain in their bones, because it’s gone to the bones, or if they’re losing a lot of weight because of the amount of cancer that they have, are usually heralded when it’s late.  So, it’s a very tricky diagnosis to make early.  


Dr. Linda Austin:  I would think so, especially because smokers who are prone to lung cancer are also prone to other lung ailments, such as bronchitis, and often have coughs, and those coughs often get better and worse of their own accord, so it must be very hard to know when to take it seriously.


Dr. James Ravenel:  Right.  It’s going to overlap a lot with some of those conditions and, quite honestly, we sometimes find lung cancers serendipitously, when we are doing x-rays to look for chronic bronchitis or emphysema or other related conditions. 


Dr. Linda Austin:  Well, then, that begs the question, if it can be hidden, would there be value in somebody who is at high risk, let’s say somebody who’d been a heavy smoker for a long time, in having, let’s say, an annual lung exam or x-ray, much as, let’s say, women have mammograms?


Dr. James Ravenel:  Well, we would like to hope so.  However, there were several studies in the 1970s that looked at annual chest x-rays as a means for finding and detecting lung cancer earlier, enough to make a difference.  And, while these studies are interesting in that they found more lung cancers, more early-stage lung cancers, that is, those that could be treated surgically, they didn’t find a reduction in late-stage lung cancers and they did not find that lung cancer mortality in a screened group was better than in an unscreened group.  So, that led to the conclusion that although we might things earlier, we’re not impacting lung cancer mortality by chest x-ray screening.


Dr. Linda Austin:  So, explain that a little more.  That might be hard for some people to grasp why that would be so.


Dr. James Ravenel:  Well, certainly, some of the lung cancers that we found, that we thought were caught early enough, had actually spread and we just weren’t able to detect that spread.  So, even though they were able to be treated with surgery, they may not have been actually able to be cured and we just didn’t know it at that time because we were picking it up where it was earlier, so the spread of disease was also earlier. 


The other theory out there is that some lung cancers, like some breast cancers, may not be significant enough to cause metastatic disease and that, to some extent, we are removing some of these more indolent tumors and calling it a cure when, perhaps, some of these tumors would not have caused any symptoms throughout the patient’s lifetime.


Dr. Linda Austin:  I see.  So, by indolent, then, you mean that it’s just kind of a sleepy old tumor and it’s just kind of sitting there and it wasn’t really going to amount to anything anyway.


Dr. James Ravenel:  Right.  Very slow growing and such that, depending on what other problems somebody has, it may not have ever been a presenting symptom.  So, we only found it because we did the x-ray, we did the CT scan, and we took it out and we thought we had done something good, and we probably did, but by the same token, we don’t know that we’ve really impacted their overall mortality and survival.


Dr. Linda Austin:  So, are there, now, currently, any sorts of guidelines or recommendations for screening for lung cancer?


Dr. James Ravenel:  None of the major societies recommend screening for lung cancer.  The study that’s gotten the most press is the CT scan.  The idea behind doing a CT scan is that you can find these cancers even earlier.  If you looked at chest x-rays, the typical size of a detected lung cancer is about the size of your thumb.  With CT, it might be down to about the size of your pinkie or about one centimeter.  So, the question really is, is that early enough?  And do we know whether detecting these nodules that early will make a difference?  And that’s been the subject of a lot scrutiny.


There’s a trial that’s been going on in the state of New York and across the country called the International LCAP, and they report in the New England Journal that almost 80-85 percent of the cancers they detected were early-stage and therefore curable.  The problem with the study is that it doesn’t have a control group and, from that perspective, we don’t whether early detection will translate into a mortality benefit.  Mortality benefit is what we look at when we decide whether screening is a beneficial process.


Dr. Linda Austin:  Let’s walk through, if we could, Dr. Ravenel, the diagnostic workup of somebody with a lesion, just to kind of understand what the steps are, from your point of view.  Let’s imagine a patient comes in to their family practice doctor, their internist, or their pulmonologist, and let’s say they have weight loss and they’re coughing and they say that they don’t feel so good, the first step would be, what?


Dr. James Ravenel:  In almost all cases, the first step is going to be a chest x-ray because that can detect certain things like a pneumonia or chronic bronchitis.  In some cases, that might give them a specific disease to treat without doing more expensive testing, such as a CT scan.  Now, let’s say on that chest x-ray, the radiologist sees a pulmonary nodule.  In general, in somebody who’s over 40, our first concern is, is that cancer and how do we find out whether it’s cancer or not?

So, what we will recommend is a CT scan.  And, depending on it where it is in the lung on the chest x-ray, we may or may not choose to give intravenous contrast material to help light up or make the aorta and the pulmonary arteries turn white so that we can distinguish that from any other abnormalities that might be in the chest.


Dr. Linda Austin:  Now, if you were not to see a nodule, would you be reasonably sure that those symptoms were not caused by cancer?


Dr. James Ravenel:  That’s always a difficult clinical question, not only for us as radiologists, but for physicians.  I think that, in individual cases, in discussion with your physician, you may just ask whether a CT scan would be a reasonable next step to ensure that there are no nodules present.  As I said, we’re talking about the difference between two centimeter lesions and one centimeter lesions.  We certainly don’t see everything on chest x-ray.  We know we see more with CT scans.  I think it’s really a combination of the discussion between a patient and their physician and a decision as to whether they may or may not want to undergo further testing.


Dr. Linda Austin:  And, I would guess, then, that said conversation or the conclusion would be very different if it were, let’s say, a 30-year-old nonsmoker, versus a 60-year-old two pack a day smoker, right?


Dr. James Ravenel:  Absolutely.  I think a lot of that plays into it.  In general, people under 40, do not get lung cancer.  There are rare exceptions, and we all know of rare exceptions, but, in somebody under 40, I would not be particularly concerned, and I would be very comfortable with a normal chest radiograph.  In somebody who’s 60 and has smoked and has some signs of emphysema and a chronic cough then, perhaps, it’s more reasonable to take the next step.  The question might also come up, why not do a CT scan, wouldn’t that be easier, it finds more things?  And that becomes part of the issue that we struggle with.


When we do CT scans, we certainly find abnormalities.  We find things that are diseased and that can be treated.  We also seem to find lots of things that we don’t know what to do with.  We find little nodules that are three or four millimeters in size.  Some of these may turn out to be a cancer; most of them do not.  If you looked at a high-risk population, more than 90 percent of these nodules that we detect, that are even four to five millimeters in size, are nothing.  They’re little scars.  They’re small lymph nodes in the lungs.  They’re the reaction of the lung to a prior infection, and they don’t grow.  But, because they look similar in appearance to what we think might be an early lung cancer, we have to make some decisions about what to do with them.  Some of these findings can be very anxiety-provoking and, perhaps, in some cases we would argue that maybe it was better that you don’t know.


Dr. Linda Austin:  I’ve certainly seen cases of that, where findings that proved in the end to be very benign actually caused a tremendous amount of anxiety and, sometimes, even a change in life decisions because the person thought they had a very serious illness.  So, you don’t want to overdiagnose or underdiagnose, and I’m sure that that’s always the challenge for a radiologist.


Dr. James Ravenel:  Exactly.  We are constantly finding these little nodules.  About 20 percent of the chest CTs that we do for reasons other than looking for cancer have at least one of these small nodules, and it’s a challenge for us because we have to decide, what is my level of suspicion, do I want to get somebody worried or worked up over this, and how soon should they be followed up? 


If it’s a very small nodule, we may not be able to detect growth for 6-12 months, even if we did more frequent CT scans.  So, we frequently will recommend to somebody that they just come back in a year, almost like you would for your other annual screening tests, such as a mammogram for women.  Or we may say, we’re very concerned about this, it has some features, the borders are irregular.  It might look more like what we think is an early lung cancer, but if we can’t do anything to prove that then we have to follow it up.  And we’ll typically follow that up at a closer interval, maybe three months.


So, there’s a large amount of decision-making on the part of the radiologist to decide how suspicious he is of the nodule.  He will take into account the appearance of the nodule, its location, and the patient’s symptoms.  Obviously, like you said, in a 40-year-old nonsmoker, we’re probably not going to be very concerned and may simply recommend one follow-up.  We may say that the chance of this being malignant is so low as to not warrant follow-up.  Or, we may say, given the look of it, and it’s a 60-year-old smoker, there’s a much greater chance of it being lung cancer, maybe you should come back sooner and see if we can detect growth in it.  Growth is really going to be our measure of the potential for cancer. 


Dr. Linda Austin: Now, what happens then?  You mentioned that the patient might go to a CT scan.  Let’s imagine that it does look worse, what would the next step be?


Dr. James Ravenel:  There are several different pathways that we might go by.  One test that we oftentimes will do in suspected lung cancer is a PET/CT.  The PET/CT looks at the metabolic activity of the lesion.  So, if we weren’t sure whether this was an aggressive lesion or not, we might do a PET/CT, usually for nodules that are greater than one centimeter in size.  And if it shows metabolic activity then we are very concerned and we’ll recommend either a biopsy or, perhaps, if it’s the only site that we find on that PET/CT, going directly to a surgeon and asking whether it’s worth doing a surgical procedure to remove the lesion. 


If it does not show increased activity then it’s got a very strong likelihood of being benign.  And, oftentimes, in those situations, we’ll, depending on, again, the appearance of the lesion, the location, and the patient’s other presenting symptoms and risk factors for lung cancer, say this is a benign lesion and not to worry about it.  Or we may say, although it doesn’t have a lot of metabolic activity, suggesting it may be a less aggressive lesion, we still want to follow it to make sure it’s not growing.  And if it’s growing, we may choose to do something different.


Dr. Linda Austin:  I think there’s more to talk about in this area.  Let’s end this podcast now though and continue, in Part 2, talking about the journey of a cancer patient.  Thank you.


 If you have any questions about the services or programs offered at the Medical University of South Carolina or if you would like to schedule an appointment with one of our physicians, please call MUSC Health Connection:  (843) 792-1414.

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