Initial signs of a recurrence of glioblastomas could be detected more than six months earlier than otherwise possible using standard clinical methods, according to a study by researchers from Karl Landsteiner University of Health Sciences in Krems.
Lack of oxygen and specific changes in the microvascular architecture are previously undetected and very early indications of the return of a brain tumour following previous surgical intervention, note the study based on a retrospective analysis of special MRI data from 56 patients.
“We were able to identify a change in the vascular architecture where the brain tumour would eventually recur fully 190-days before a conventional MRI diagnosis could be made,” said Prof. Andreas Stadlbauer, a researcher from the Institute of Medical Radiology at St. Pölten University Hospital (KL Krems), who led the team.
This was made possible by measuring biomarkers for certain physiological values in the brain tissue using MRI. The team of researchers looked at earlier MRI scans from patients who had had a recurrence of the glioblastoma later on. In the areas of the brain where this was observed, they noticed changes in the physiological biomarkers over a period of a year before the tumour recurred and were able to identify characteristic patterns.
These patterns included a decrease in vessel density in the brain tissue – which was reflected in reduced blood supply – fully 190 days prior to the radiological diagnosis. Increasing lack of oxygen which could also be measured using MRI was also among the changes noted. This led to the formation of tiny vessels and an increase in vessel density 120 days before the radiological diagnosis. A month later, this led to an increase in oxygen supply.
“We observed two different phases in the manifestation of a recurrent glioblastoma” said Prof. Stadlbauer. “Infiltrating tumour cells – that cannot be killed during preliminary treatment – recruit existing microvessels to ensure their own supply, but end up weakening and destroying them. This was the process that we observed in the form of decreased vessel density. The related decline in oxygen supply and the resulting tissue hypoxia triggers the formation of microvessels, which – with a delay of 30 days – is seen in the restoration of blood supply and improved oxygen and nutrient supply that plays a decisive role in aggressive tumour growth.”
The observations made in patients for the first time provide solid foundations for the development of an MRI-based early diagnosis technique for recurrent glioblastoma, noted the study published in Clinical Cancer Research.
Glioblastoma is a form of malignant brain tumour with diffuse infiltration into the adjacent brain tissue. This characteristic makes it particularly difficult to fully remove tumours, meaning that supplementary treatments such as chemotherapy and radiotherapy are also required. But even so, in the vast majority of cases, the tumours return within a short space of time. Diagnosing recurrence at a very early stage is difficult, but crucial given the decisive role it plays in determining the patient’s life expectancy.