MRI, Macrophages Help Predict Prognosis in Glioblastoma

Damian McNamara

April 22, 2016

LOS ANGELES — Predicting prognosis for patients with aggressive glioblastoma multiforme tumors is a challenge, but it can be easier when MRI features are combined with molecular subtype information, new research suggests.

"Glioblastomas are not all the same," said Jean Zhou, MD, from Dunedin Public Hospital in New Zealand. This is one of the confounders affecting accurate prognosis.

Although MRI features alone are insufficient to predict glioblastoma multiforme outcomes, Dr Zhou told Medscape Medical News, "malignant immune cells status — the presence or absence of tumor-associated macrophages — in combination with specific tumor features on MRI can predict patient outcome."

Dr Zhou and colleagues studied 225 adults with primary glioblastoma multiforme who were enrolled in a New Zealand brain tumor study.

All were treated at one of three tertiary care centers from 2004 to 2014, where they were evaluated prior to surgery with a clinical 1.5 T MRI scanner. Three independent radiologists, blinded to patient and clinical factors, evaluated the images for tumor margin regularity, cystic appearance, necrosis, hemorrhage, multifocality, and peritumoral edema grade.

Tumor Features and the Molecular Signature

Combining these six MRI tumor features and the molecular signature helps predict tumor treatment response and patient survival, the investigators report in an electronic scientific exhibit here at the American Roentgen Ray Society 2016 Annual Meeting.

Molecular signature elements included tumor-associated macrophages; investigators used immunochemistry to type tissue sections stained for macrophage marker CD163.

The researchers also identified whether tumors were positive or negative for alternative lengthening of telomeres. They assessed each of the six radiologic MRI features as an independent variable in relation to patient survival. Then they assessed the features in each molecular subgroup and correlated them with patient survival. They used log-rank survival graphs to show patient survival outcomes in each molecular group.

This study is the second phase of the research. In a previous study, the investigators assessed how telomere profile and tumor-associated macrophages with different immune signatures affect prognosis in these patients (Mod Pathol. 2016;29:212-226).

"There is mounting evidence that telomere dysregulation may play an important role in glioblastoma development. This study, interestingly, found that conventional MRI features may add prognostic value when combined with molecular markers of telomere dysregulation," said Carlos Zamora, MD, PhD, from the University of North Carolina at Chapel Hill, who is not involved with the research.

"I would like to see such results independently validated, perhaps incorporating advanced MRI techniques, such as diffusion tensor, perfusion, and microvascular permeability," Dr Zamora told Medscape Medical News. "Which specific imaging or molecular paradigm will eventually provide the most robust predictor continues to be a focus of intensive research."

Dr Zhou and Dr Zamora have disclosed no relevant financial relationships.

American Roentgen Ray Society (ARRS) 2016 Annual Meeting: Abstract E1329.

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