Use of PET in Staging Pleural Mesothelioma

Mesothelioma News

Positron Emission Tomography Indicated Spread of Pleural Mesothelioma

October 1, 2003 — Researchers at Memorial Sloan–Kettering Cancer Center in New York recently studied the use of the imaging technique, positron emission tomography (PET) to indicate the extent to which cancer has spread in pleural mesothelioma patients (J Thorac Cardiovasc Surg. 2003 Jul; 126(1): 11–6). Other procedures such as computed tomography (CT scans) and magnetic resonance imaging (MRI scans) have not always proved helpful in determining pleural mesothelioma stages.

In a PET scan, sugar compounds are labeled with a signal–emitting tracer and then are injected into the patient. A scanner records the signals these tracers emit. A computer reassembles the signal into images that reflect the levels of uptake of the sugars. Because cancers metabolize sugars at a higher rate than normal tissues or organs, the theory is that PET scans show where there is abnormal metabolic activity.

In the current study, 63 pleural mesothelioma patients received PET scans using the tagged sugar compound F–18–fluorodeoxyglucose. The results of these scans were compared with information gathered from surgery and pathology reports.

PET scans for localized pleural mesothelioma were somewhat disappointing, yielding sensitivities of only 19% for tumors and 11% for nodes. However, PET scans were more successful in detecting the spread of the disease to more distant lymph nodes in the mediastinum (the space in the chest between the pleural sacs of the lungs) and beyond. In these cases, PET scans located metastases or cancer spread to lymph nodes on the opposite side of the body from the main tumor (N3 disease), and to more distant areas (M1 disease). The study is in contrast to one done at the University of Pennsylvania in which PET was useful both in detecting mesothelioma and staging the disease, distinguishing between malignant mesothelioma and benign disease with a sensitivity of 91% (Chest. 1998 Sep; 114(3): 713–22).

The Sloan–Kettering researchers concluded that more work needs to be done concerning the use of PET. They emphasized that having more knowledge of the stages of mesothelioma cancer could eliminate the necessity of using diagnostic surgery such as thoracotomy on some pleural mesothelioma patients.