Hi, I'm Leslie Quint from the Department of Radiology at the University of Michigan. Welcome back. Today's talk is entitled, Recommendations for Management of Small Incidental Solid Lung Nodules. The objective for today's talk is to present guidelines for the management of small incidentally, detected, solid lung nodules on CT scanning. Let's start out with a pre-lecture question. I'm going to read you a statement and you can tell me if you agree or you disagree with this statement. So, here it goes. If I saw a solitary incidental six-millimeter noncalcified lung nodule in a healthy 55-year-old man with no smoking history, I would invoke the Fleischner Society guidelines in my report. So you can choose whether you agree with this statement, you disagree, or whether you're unsure. We'll get back to this at the end of the talk, and we'll have pre-lecture question number two. So, do you agree or disagree with this statement: if I saw a solitary six-millimeter noncalcified lung nodule in a middle aged man with colon cancer, I would invoke the Fleischner Society guidelines in my report. So, do you agree, agree if the patient is afebrile, disagree, or are you unsure? Okay, so let's get started. Small incidental lung nodules are very common not just in smokers but also in nonsmokers. In fact, about half of smokers older than age 50 have small nodules on thin-section CT scanning. The vast majority of these nodules turn out to be benign and many of them represent granulomas particularly in histoplasmosis endemic areas, such as the Central United States where I live and where I work. There's an increased chance of malignancy with increased nodule size. So here are some numbers. Less than one percent of nodules under four millimeters in diameter in smokers turn into lethal cancers. Whereas, if we look at larger nodules, about eight millimeters in diameter, about 10-20 percent of those turn into lethal cancers in smokers. So you can see that size does have an influence on the chance of malignancy. However, you can turn these numbers around, and in fact, 80-90 percent of eight-millimeter diameter nodules in smokers are actually benign. So, the bottom line here is, most small incidental nodules even in smokers are benign. Not just size but also increased age correlates with increased chance of malignancy. Lung cancer is uncommon under the age of 40 and it's rare under the age of 35. So, what do we do if we encounter an incidental lung nodule on our CT scans? The very best thing we can do is look for comparison imaging. If a nodule is solid and if it's stable for at least two years, then we can say it's benign. If we don't have comparison imaging or we don't have two years of stability, the next best thing we can do is to look for benign morphologic features and clinical characteristics. For a discussion on that, I would refer you to Dr. Arenberg's lecture on the probability of lung cancer. Okay, so what do we do if we see an incidental lung nodule, if we don't have two years of stability, perhaps we don't have comparison scans, and we don't have clearly benign morphologic or clinical features? So, the nodule in other words is indeterminate. The best thing we can do is use published evidence-based management guidelines. What we use in our practice are the Fleischner Society guidelines which were updated in 2017. These guidelines are based on patient risk, particularly history of smoking, as well as nodule size and nodule multiplicity. Here are the Fleischner Society guidelines for the management of incidentally detected, solid lung nodules in adults. This looks a little complicated. I think if you go through it, you can figure things out but I would just like to point out a couple of features. First of all, the nodules should be measured using an average of long and short axis diameter rounded to the nearest millimeter. Secondly, we can measure the nodules using diameter or using nodule volume. Currently, most practices use nodule diameter but we are moving more and more in the future to using volumetry. Okay, at this point, I would just like to point out some caveats for using these guidelines. Remember that the guidelines only apply to adults older than age 35 or age 35. That is because lung cancer is very rare under the age of 35. Another potential pitfall for using these guidelines is to remember that they are only for incidental nodules. The guidelines do not apply in the screening setting. If you're doing screening, you should use guidelines that are meant for that situation and what we use are the Lung-RADS guidelines from the American College of Radiology. Another feature to point out is that the guidelines are not meant for cancer staging and follow-up. Those patients will be managed according to the type and stage of their known cancer. Finally, the guidelines are not for immunocompromised patients or for patients with clinical evidence of infection because those types of nodules may actually just represent a focus of infection and short-term follow-up may be appropriate. Here's such an example. In this patient, we saw an incidental left lower lobe nodule. It was somewhat ill-defined. We did not invoke the Fleischner Society guidelines because the patient had a fever, and in fact, this nodule resolved within the next few weeks. This was just a region of infection. There are other published evidence-based guidelines that you may wish to use. They're overall similar to the Fleischner Society guidelines. There are guidelines from the American College of Chest Physicians and from the British Thoracic Society. This latter management strategy applies to not just incidental nodules but also to screen-detected nodules. Okay, and that brings us back to our questions. So, we'll start with the one listed here and tell me whether you agree with this statement. If I saw a solitary incidental small noncalcified lung nodule in a healthy middle-aged man with no smoking history, I would invoke the Fleischner Society guidelines in my report. The best answer here is probably you should agree that this is a good situation for using the Fleischner Society guidelines, and that strategy would suggest that we get a follow-up CT scan in 6-12 months, and if the nodule is stable, then consider an additional CT scan at 18-24 months to establish longer term stability. Then our second question, if we saw a similar nodule in a man with colon cancer, would you invoke the Fleischner Society guidelines in your report? The best answer here would be to disagree. This is not the situation where we would use these guidelines because this may represent a metastasis and this patient will be followed according to protocol for his known cancer. Okay, so that brings us to our take home points. For indeterminate solid nodules, it's best to use published evidence-based management guidelines and to use them when clinically appropriate remembering their limitations. In addition, we need to consider the entire individual patient scenario. Remembering that conservative management may be indicated for very elderly patients and patients with major co-morbid disease. So even though the guidelines might suggest that we get more tests, biopsies, or perhaps take the patient to surgery, that may not always be justified in that individual patient. With that, I thank you very much for your attention.
