Dr. Kim L. Sandler provides an overview of lung cancer screening methods and remarks on the accuracy of test results.
PUBLISHED November 08, 2017
Philippa Cheetham, MD: So, let’s talk about what screening involves. If a patient hits age 55, they go to their primary care doctor. Do they get called in automatically or does the patient have to say, “Hey, I’m 55 now, I’ve read that I need to be screened for lung cancer”? How do they get to be picked up to be screened in the first place?
Kim L. Sandler, MD: I think it depends on your institution and the doctor that you’re seeing. We would really like to have a much more automated system where providers are made aware that their patient qualifies at a certain age and a certain smoking history. That can be very difficult, particularly with smoking history because it’s difficult to get an accurate representation. Sometimes stories change and we don’t know if they’ve really hit that 30-pack-year mark. What we’re trying to do is educate our providers and educate our patients at the same time, so that your provider may say to you, “I think you will qualify based on your age and pack-years.” But also, the patient can say, “You know, I’ve seen some information about this. I’m not really sure if I qualify. Is this something that I should go ahead and do?”
Philippa Cheetham, MD: And the kind of screening that patients get?
Kim L. Sandler, MD: The screening itself is a CT examination. It’s a non-contrast CT, meaning that there’s no IV, there’s no needles, there’s no pain involved. The exam itself takes about 10 seconds. It’s a single breath hold, a single CT scan. I think there are some concerns about the radiation risk. The radiation is less than the amount of background radiation one would receive living at sea level for a year. And what we really try to emphasize at Vanderbilt is that this is a screening program. This is not just a scan. When you come to see us, we will sit down with you and we will perform what’s called a shared decision-making visit where we discuss all of the risks and benefits of screening, including radiation exposure. We will do targeted smoking cessation counseling with you, we will help you to quit smoking and help you to get those resources that you need, and be there to answer any questions. After the scan, we then contact both the patient and the provider with results, and if there is follow-up that’s needed before the next annual scan, we will help to schedule that.
Philippa Cheetham, MD: So, for screening nationally right now, the right test is a non-contrast CT scan of the chest.
Kim L. Sandler, MD: Yes.
Philippa Cheetham, MD: So, that is much more accurate than a standard chest X-ray, yes?
Kim L. Sandler, MD: Absolutely. And what the study did that I mentioned that was published earlier with 50,000 patients was randomize to either the non-contrast CT scan or the chest X-ray. And that’s where the 20% reduction in mortality from lung cancer came, by doing the CT scan as opposed to the X-ray.
Philippa Cheetham, MD: And we’ve heard a lot already about molecular markers, about targeting therapy. Is the CT just the only thing that we do? There’s no blood test? There’s no biological marker that we can measure in the blood like we can do for so many other cancers? It’s just the CT test.
Kim L. Sandler, MD: Not yet. I would say there’s a lot of really active research being done on biomarkers, and I think we’re getting closer and closer daily to finding particles circulating in the blood and also breath tests to look for lung cancer.
Philippa Cheetham, MD: So, if somebody is screened and they have a CT scan, it’s all clear. I’m sure for many patients who have been heavy smokers, there may be some scarring in the lungs, some abnormalities from chronic smoking exposure. Does that make it difficult to say to somebody, “Look, you really are all clear”? Can you give people a good pat on the back that the CT is clear or does it make it hard to interpret a CT if you’ve got a lot of smoking-related changes on someone’s scan?
Kim L. Sandler, MD: What we say is there are no signs of lung cancer at this time. There is no abnormality to us that suggests that you have lung cancer at this time. The likelihood of seeing something that could be mistaken for a cancer is much higher than us saying your CT scan is negative or has no signs. So, it’s much more likely that we’ll say, “Well, this is a little concerning. It may not be cancer, but we need to do some additional testing.” The specificity and sensitivity of the test, the sensitivity or our ability to detect disease is very, very high. So, it’s very unlikely for us to say you don’t have cancer and then you end up having a cancer at that time. The specificity or being able to say this certainly is a cancer is lower. Sometimes those patients would need to come back.
Philippa Cheetham, MD: And we’ve already heard that patients who have a suspicious lesion need a tissue diagnosis with a biopsy anyway. Before we bring in Chris and Carly into the discussion, you’ve talked about screening. What’s the screening interval? When should patients come back to be re-screened? Is it a standard policy for everybody that you come back at a set interval or is what you see determine whether you may bring somebody back sooner?
Kim L. Sandler, MD: As long as the patient continues to qualify both on age and their smoking history, we will recommend that they come back in a year following a normal CT scan. The recommendations will change if we see something abnormal, and we may recommend that they come back in three or six months. Or, if it’s very suspicious, we may recommend that they go ahead and have another diagnostic study like a PET/CT to look for metabolic activity or even a biopsy depending on those findings. But if the scan is negative, then we’ll recommend they come back in a year.