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The Importance of Subtype in PET Scanning for Mesothelioma Prognosis

PET scanning for mesothelioma prognosis

A new study of PET scanning for mesothelioma prognosis shows how much radioactive tracer a tumor absorbs can predict survival. This is especially true in people with the epithelioid mesothelioma subtype. 

The study comes from the Sungkyunkwan University School of Medicine in Seoul, South Korea. Researchers studied the medical records of dozens of mesothelioma patients diagnosed between 2009 and 2018.

They found that SUVmax, a key factor in PET scanning for mesothelioma, is directly related to mesothelioma survival. 

How PET Scanning Works

Mesothelioma diagnosis is challenging. Pleural mesothelioma grows quickly on the membrane around the lungs. It is one of the rarest and deadliest cancers. Positron emission tomography (PET) combined with computed tomography (CT) can help with diagnosis. 

During a PET scan, the patient gets an injection of a radioactive tracer called FDG.  Cancer cells absorb or “uptake” more of the tracer than normal cells. How much they absorb is the standard uptake value (SUV). 

The imaging scan shows the percentage of cells that absorb the maximum amount of tracer. This number is the SUVmax. Together with a CT image, SUVmax can provide vital information about a mesothelioma tumor

PET Scanning for Mesothelioma Prognosis

Doctors can also use PET scanning for mesothelioma prognosis. Prognosis is not just about predicting survival. A prognostic test like a PET scan can show if a mesothelioma treatment is working. 

Prognostic tools are especially important with fast-growing cancers like mesothelioma. If one mesothelioma treatment does not work, doctors must pivot quickly to try another one. 

The new Korean study shows how variable SUVmax can be in PET scanning for mesothelioma prognosis. Mesothelioma subtype appears to make the difference. 

Subtypes Make the Difference

Researchers looked at the records of 54 pleural mesothelioma patients. Thirty-four of the patients had the epithelioid mesothelioma subtype. Thirteen had biphasic or sarcomatoid mesothelioma. The remaining seven were unclassified.

The SUVmax values were much higher in people with non-epithelioid mesothelioma. But it did not appear to relate to how long they lived. 

“In multivariate analysis, SUVmax was significantly associated with overall survival…but not in those with non-epithelioid subtype,” writes study author Jun Hyeok Lim. The SUVmax number only related to survival in the people with epithelioid mesothelioma.

Dr. Lim and colleagues conclude that SUVmax “is an independent prognostic factor” in PET scanning for mesothelioma prognosis. But they say doctors should also consider a patient’s subtype when deciphering the SUVmax number. 

Epithelioid mesothelioma is by far the most common subtype. It is also the subtype that is most responsive to treatment. 


Lim, JH, et al, “Prognostic value of SUVmax on 18F-fluorodeoxyglucose PET/CT scan in patients with malignant pleural mesothelioma”, February 18, 2020, PLoS One, https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0229299

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