Radiology: Controversy over Screening
Guest: Dr. James Ravenel – Radiology, MUSC
Host: Dr. Linda Austin – Psychiatry, MUSC
Dr. Linda Austin: I’m Dr. Linda Austin. I’m interviewing Dr. James Ravenel, who is Associate Professor of Radiology and an expert in the area of thoracic imaging; of the chest. Dr. Ravenel, screening of all sorts, whether it’s screening for heart disease or depression, or lungs, or lung cancer; or whatever, has become very popular these days. What are your feelings about screening? There’s certainly an upside. Is there any downside to it?
Dr. James Ravenel: Well, when we perform a screening test, we’re looking to find a disease before it becomes symptomatic: i.e. causes you problems. And, in the process of that, we’re looking, usually, through some kind of imaging to find suspicious abnormalities that may or may not represent a disease process. So, for instance, with lung cancer screening; which is not currently recommended, the test that’s done in clinical trials is the CT scan. And, while that is very good at picking up lung cancer at a size of 1 to 1.5 centimeters; fairly early lung cancer, it also picks up lots of other abnormalities that may or may not be lung cancer.
Obviously, this can have profound effects, depending on what that finding is. If it’s a very small nodule, we may only be able to recommend following it up. It’s too small to show up on another test, such as a PET/CT, or it’s too small for anybody to put a needle into. And, in those cases, it’s even too small for a surgeon to feel it and take it out. So, we find many of these small nodules are a problem, because all we can recommend to somebody is to follow it.
The good news is that the vast majority of them turn out to be benign. If we looked at patients who are screened and had a nodule detected, more than 90 percent of them are benign. The difficult thing is we oftentimes do not know which ones are going to be benign and which ones are going to malignant until we’ve watched them for a certain period of time; usually two years.
Dr. Linda Austin: That’s a long time.
Dr. James Ravenel: Right. The idea behind that is we want to make sure that a lesion isn’t growing. Sometimes, we can’t detect, at that small size, very subtle growth. Measuring something going from 4 to 5 millimeters is not an easy task. As you can imagine, the shaking of your hand in one direction or the other might mismeasure a nodule. And that’s why we want to see it several times before we’re very comfortable, one, that it has or has not grown, and what to do with it.
Dr. Linda Austin: Have you seen situations where being overly concerned or overly vigilant about something picked up on a screen; an exam, has caused a clinical problem for a patient?
Dr. James Ravenel: We see this from time to time. People will get a nervous about a screening finding and they’ll want to undergo a biopsy procedure or surgical procedure to remove the lesion. Usually, the worst thing that happens is we either don’t make a specific diagnosis; which can mean more follow-up, or they have a benign lesion. That is, we did something that was invasive and it didn’t turn out to be cancer. With any of these procedures, there are risks. You can get a pneumothorax that can require having a tube or staying overnight in a hospital. There are complications, obviously, of surgery, including anesthesia. So, it’s not as simple as, if we find something, we’ll get a piece of it and find out whether it’s benign or malignant. The lesions in the lungs, depending on their location, can be very tricky and very difficult. It’s not quite as easy, or safe, as, maybe, doing a breast biopsy, for instance. The risks and benefits of doing a biopsy in the lung are different than doing biopsies in other places.
Dr. Linda Austin: And it certainly can be, at least temporarily, a life-altering event to live with the anxiety of having a lesion that nobody can tell you, definitively, what that lesion is.
Dr. James Ravenel: Right. And we see the entire spectrum in people. There have been people, having participated in our screening trial, tell me in follow-up that they were so worried about the nodule. They were worried that it might be growing, and that they might have cancer. And they were so relieved when they got their follow-up results that it hadn’t grown. And we’ve had people that really take the opposite. They say they don’t think it’s much, and they’re very comfortable with it.
I think how you’re going to react to what we call indeterminate findings is really going to impact whether you’re going to be comfortable having a screening test, in some regards. Women, certainly, go through this all the time with their mammograms, when there’s something and they’re told to return to in six months or to get a biopsy. Again, there can be a lot of anxiety around it until you have a definitive answer.
Dr. Linda Austin: I recall, several years ago, there was a change, I think, in the recommendations for mammography. I remember watching Katie Couric interview someone about that, and she was so angry. She’s quite an advocate for mammography because of a family history. And it was clear to me that what she didn’t understand is that breast cancer grows so slowly that the data on the value of mammography is not as clear-cut as one would really like to think. I mean, there are subtleties about these illnesses that are very hard to explain to lay people, especially because it’s different from one kind of cancer to another as to what the particular issues are.
Dr. James Ravenel: Right. The controversy on any of these hinges on screen detection versus symptom detection. Symptom detection would be, you have a cough and some blood in your sputum, you get chest x-ray or CT scan, and we find a cancer. That would be what we call symptom-detected. A screen-detected finding would be that you have no symptoms whatsoever, and we find it. And the real question is: does it make a difference if you get it at that screen-detected stage? We know that, certainly, lung cancers, and other cancers, grow without symptoms, and some of them become metastatic before they have any symptoms. So, what you’re really looking at is the ability to intervene before a lesion progresses outside of that local organ, for instance.
With lung cancer, we’re not 100 percent sure we’re necessarily detecting it. We don’t know whether its size; which we think is important in many respects, or tumor biology. That means: is the tumor itself very aggressive? A very aggressive tumor might have metastasized before it even gets to the point where we can see it on a chest x-ray or chest CT. A very indolent tumor might be picked up earlier on a chest CT; and adequately picked with a chest x-ray, and might not have ever needed treatment. These are very complicated and individual issues. There’s no question that the pace of a cancer is very dependent on the individual, as well as the cancer itself.
Dr. Linda Austin: Dr. Ravenel, thanks so much.
Dr. James Ravenel: Thanks.
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