The role of PET scans in following response to treatment remains a grey area compared with staging, where PET scans have become a remarkably helpful tool. I don’t routinely use PET scans for following advanced disease, where a CT 6-8 weeks after starting treatment can still do a very good job of telling us about whther a cancer is responding, stable, or progressing.

While it’s true that a PET scan can potentially be more sensitive than a CT at detecting subtle changes, I’m wary about making treatment decisions too rapidly based on changes that may be too subtle. If we see the SUV rise from 6 to 8 but the size of a tumor remains stable, I’d be very reluctant to just declare the treatment to be a failure. We don’t have so many very effective treatments for lung cancer that I’d want to have too low a threshold to change treatments if the differences are so subtle that they can’t be detected on a CT scan. My general feeling is that if it’s so subtle that a CT doesn’t show changes, it’s too subtle to alter treatment decisions.

There are still some situations in which I’d use a PET scan to follow disease, and I don’t think it’s wrong to use it more frequently, but Dr. Pennell has also expressed his belief that PET scans are overused in advanced lung cancer, and many other experts feel similarly. It’s a place where there’s still room for different strategies.

-Dr. West