ELCC 2018 | Establishing guidelines for categorizing nodules in lung cancer screening

I spoke this morning, I gave a talk about pulmonary nodules that are detected at screening, and I called it ‘walking the tightrope’ because it is a really delicate balance that we have to tread, and it’s something that we’re learning more and more about. I was able to present some of the original data supporting the use of CT screening for early detection of lung cancer and to improve lung cancer specific mortality from the National lung screening trial, but also lots of other data that has come since then from studies like NELSON, the Dutch Belgian study, and the UK lung cancer screening study, the UKLS, as well as other studies that have helped us to learn more about how best to handle these difficult primary nodules that we see more and more commonly in routine clinical practice, but even more so if CT screening comes in and with the advent of it.

One of the things that I was trying to highlight was that there are a number of risks and harms that can be associated with lung cancer screening, such as false positives, indeterminate nodules, the false negatives, and also radiation induced damage caused by repeat CT scanning, but also things like overdiagnosis and interval cancers. And I think the main summary from my presentation was to really explain that by managing and by improving our management of pulmonary nodules, we can really reduce all of these harms because they are all related to this one sort of issue. And there have been a number of different strategies that have been brought about by the Deuter guidelines and societies putting guidelines in place, or just as a result of emerging evidence that hopefully will inform future updates of guidelines that can really help us to do that.

One of the main things is firstly to be fully aware of this problem and I think be very open and honest to patients about the fact that there are these things called indeterminate nodules, that the majority of them are not malignant, and therefore perhaps should be called indeterminate nodules not positive results from screening. So that’s the first take-home message the second take-home message is that the way that we manage them is really key, and there are a number of strategies that we can implement, so the British thoracic society guidelines for example really advocates of using volume instead of diameter when we look at these nodules on a scan, and using something called volume doubling time, which is to assess the rate of growth, as being much more accurate than using two-dimensional measurements. So that’s one.

Other things that have been used also by guidelines including that in the United States, the lung-RADS guideline, which is to perhaps a adopt a more conservative approach to some nodules which are ground glass which are not solid, and therefore are much less likely to be malignant and we can be much more relaxed about them. And obviously if they show signs that become worrying then we act at that point, but certainly not to rush in. There are also other strategies that we can implement if screening is advocated, such as perhaps having a risk-based prediction of how often you should have your screening, and this could perhaps also be very useful as there is data to suggest that if you have a negative screen at the first screen that you have a very much reduced risk of having malignancy in the long term. So there are these various different strategies that we can employ, but ultimately we have to balance everything with the false positives and the false negatives, as usually there’s a trade-off against this and ultimately we don’t want to be missing cancers either.