Morphological and functional brain changes in chronic cancer‐related pain: A systematic review

Abstract

The purpose of this study was to perform a systematic review of the available literature on morphological and functional brain changes measured by modern neuroimaging techniques in patients suffering from chronic cancer‐related pain. A systematic search was conducted in PubMed, Embase, and Web of Science using different keyword combinations. In addition, a hand search was performed on the reference lists and several databases to retrieve supplementary primary studies. Eligible articles were assessed for methodological quality and risk of bias and reviewed by two independent researchers. The search yielded only four studies, three of which used MRI and one PET‐CT. None of the studies measured longitudinal morphological (i.e., gray or white matter) changes. All studies investigated functional brain changes and found differences in specific brain regions and networks between patients with chronic cancer‐related pain and pain‐free cancer patients or healthy volunteers. Some of these alterations were found in brain networks that also show changes in non‐cancer populations with chronic pain (e.g., the default mode network and salience network). However, specific findings were inconsistent, and there was substantial variation in imaging methodology, analysis, sample size, and study quality. There is a striking lack of research on morphological brain changes in patients with chronic cancer‐related pain. Moreover, only a few studies investigated functional brain changes. In the retrieved studies, there is some evidence that alterations occur in brain networks also involved in other chronic non‐cancer pain syndromes. However, the low sample sizes of the studies, finding inconsistencies, and methodological heterogeneity do not allow for robust conclusions.

Pain after cancer: Time to move towards a mechanism‐based approach!

“…In a systematic review on available tests for measuring or testing indices of central sensitization, brain imaging to discover structural and/or functional changes and quantitative sensory testing (QST) to assess somatosensory alterations were the most reported measurement instruments (den Boer et al, 2019). Contrary to research on brain alterations in patients with chronic musculoskeletal pain, little is known about anatomical, functional, and neurochemical changes in the brain of cancer survivors with chronic pain, as evidenced in the systematic review of Vande Vyvere et al (2024), calling for further research in this domain. Brain study in these patients is particularly specific and relevant, as many cancer patients, depending on the cancer type and stage, are pain free at the moment of diagnosis, but a substantial part develops chronic pain after treatment.…”