Pseudoprogression versus true progression in glioblastoma: what neurosurgeons need to know

Abstract

Management of patients with glioblastoma (GBM) is complex and involves implementing standard therapies including resection, radiation therapy, and chemotherapy, as well as novel immunotherapies and targeted small-molecule inhibitors through clinical trials and precision medicine approaches. As treatments have advanced, the radiological and clinical assessment of patients with GBM has become even more challenging and nuanced. Advances in spatial resolution and both anatomical and physiological information that can be derived from MRI have greatly improved the noninvasive assessment of GBM before, during, and after therapy. Identification of pseudoprogression (PsP), defined as changes concerning for tumor progression that are, in fact, transient and related to treatment response, is critical for successful patient management. These temporary changes can produce new clinical symptoms due to mass effect and edema. Differentiating this entity from true tumor progression is a major decision point in the patient’s management and prognosis. Providers may choose to start an alternative therapy, transition to a clinical trial, consider repeat resection, or continue with the current therapy in hopes of resolution. In this review, the authors describe the invasive and noninvasive techniques neurosurgeons need to be aware of to identify PsP and facilitate surgical decision-making.

Laser interstitial thermal therapy (LITT) for pediatric low-grade glioma—case presentations and lessons learned

“…On follow-up imaging, lesions' volume usually transiently increases in the first 2-4 weeks after the procedure and then gradually decreases, returning to pre-ablation volumes around 3 months after the procedure [25]. This pseudo-progression effect is thought to be mediated by post-ablation inflammatory processes due to thermal necrosis, which, like other ischemic processes, leads to increased vascular permeability and, consequently, increased contrast enhancement [26]. Lesions continue to decrease in volume over time, but it is not uncommon for a small residual enhancing lesion to remain even 6-12 months after the ablation (Fig.…”

Residual pattern of the hyperintense area on T2-weighted magnetic resonance imaging after initial treatment predicts the pattern and location of recurrence in patients with newly diagnosed glioblastoma

“…Only patients who did not have residual or progressive enhanced lesions at the end of initial treatment with concomitant radiotherapy and temozolomide were included to investigate the signi cance of hyperintense areas on T2WI. The enhancement, which highly indicated pseudoprogression, was also excluded due to the di culty in discriminating it from true progression and the signi cant edema caused by this entity [23]. Additionally, we excluded cases that showed factors modifying the distribution of hyperintense area on T2WI as shown in Fig.…”

Advances in Intraoperative Glioma Tissue Sampling and Infiltration Assessment

“…These highly accurate and efficient models provide unique classification abilities that may extend the utility of these intraoperative tissue analytic methods. For example, it is well known that recurrence presents glioma surgeons with the challenge of distinguishing true progression from pseudoprogression; however, combining CNN and SRH has demonstrated a diagnostic accuracy of 95.8% [89,90]. Recently, other groups have reported the use of intraoperative nanopore sequencing combined with advances in machine learning algorithms to deliver molecularly subclassified diagnoses within 90 min [91,92].…”