What is pseudoprogression?
Pseudoprogression is a swelling or contrast enhancement on a brain scan. This suggests tumour progression or recurrence, when it is in fact treatment effect. Pseudoprogression can stabilise without additional treatments and often remains clinically asymptomatic. For example, radiotherapy and surgery can cause inflammation post treatment, often months after the event. On a scan this might look like the tumour is progressing, but in actual fact it isn’t. The only way you would know would be by having active surveillance to see if it reduces over time. If it does then you know it is pseudoprogression. No surgeon would operate just to confirm a diagnosis of pseudoporgression.
Why does pseudoprogression matter?
It really matters. The significance came to front of mind this month as a patient, who was about to sign onto a trial, had a scan showing progression. Or was it? Having the opportunity of a trial taken away is devastating, even more so if access to the trial is denied and pseudoprogression is diagnosed; the trial ship will have sailed and so it will be too late.
So from a human perspective pseudoprogression generates so many feelings – anxiety, fear, sadness. All of the feelings that we experienced on first diagnosis come back and although they are a well navigated path, these feelings are as powerful as ever. Time doesn’t make it easier, or us more accepting of them – they are as visceral as the day we were told ‘you have a brain tumour’.
From a clinical perspective pseudoprogression complicates matters. It can lead to premature discontinuation of treatment, owing to the false judgment of progression. It can lead to patients being denied access to treatments that may be of benefit, or, as we saw this week, being denied access to a trial. The only way currently to see definitively if it is true progression of tumour or pseudoprogression would be through surgery – and no surgeon would operate just to find out. So this does cause significant challenge to clinicians.
What is the solution?
A solution is TRAMs (Treatment Response Assessment Maps), a new development in MRI technology. TRAMs allows for easier predicted diagnosis of progression or pseudoprogression by giving high resolution of tissue. Tissue either shows up as blue (tumour tissue) or red (non-tumour tissue). Patients have to have a short MRI scan more than an hour post contrast injection. If this could be available in every centre, it might not remove the emotion that comes with every scan, but it would mean that we could have more certain conversations about clinical decision making going forward.
 Ingrid Sidibe et al, Pseudoprogression in GBM versus true progression in patients with glioblastoma: A multiapproach analysis, Radiotherapy and Oncology, Volume 181, 2023 https://doi.org/10.1016/j.radonc.2023.109486