Italian Studies Reveal Shortcomings of PET/CT for Identifying Malignant Mesothelioma

Malignant mesothelioma is challenging for many reasons. The rare and fatal asbestos-related form of cancer is only diagnosed in approximately 3,000 patients per year, and this means that studies assessing the effectiveness of treatment are necessarily limited in scope. The disease is not only notoriously resistant to traditional treatment, but also has a long latency period that leads to diagnosis not being confirmed until it is in an advanced stage. For all these reasons, early diagnosis is extremely important. A recent study conducted by Italian researchers has called into question the accuracy of PET/CT, a popular diagnostic tool.

Study Reveals PET/CT False Negatives

According to research out of the Department of Thoracic Surgery, Fondazione Policlinico Universitario “A. Gemelli”, IRCCS, Università Cattolica del Sacro Cuore, in Rome, Italy, the results of PET/CT scans are particularly unreliable in patients who are either in the very earliest stages of mesothelioma or who are older.  

The study analyzed 9 years’ worth of PET/CT scans conducted on 141 patients who were suspected of suffering from mesothelioma.  The researchers found that despite the diagnostic test’s reputation for accuracy, the PET/CT results for one of three of the older patients who were later diagnosed with Stage 1 pleural mesothelioma incorrectly showed up as negative. An even higher percentage of the overall group (regardless of age) also reported negative, even though they were actually in the earliest stage of the disease. These false negatives could easily have delayed treatment and led to shorter survival times. Fortunately, the patients were also tested using highly accurate blood and tissue samples.

Study Shows Limited Use for PET/CT in Diagnosing Mesothelioma

Though PET/CT is an innovative diagnostic tool, this study revealed that it has significant limitations for diagnosing malignant mesothelioma, and especially Stage 1 malignant mesothelioma. This is unfortunate, because the earlier mesothelioma is diagnosed, the more treatment options the patient has available to them.

Notably, the researchers found that different types of mesothelioma cells reacted differently to the dye used in PET/CT scans. Sarcomatoid or biphasic mesothelioma cells had higher absorption levels of the dye than was true of epithelioid mesothelioma cells, which are the most commonly seen cell type. 

In reviewing their results, the researchers indicated that care needs to be taken in choosing PET/CT for diagnosis of the rare disease, particularly when patients are older. They wrote, “A low fluorodeoxyglucose uptake might be observed in more than 10% malignant pleural mesotheliomas, especially in early-stage tumors affecting elderly patients.” 

If you are at risk for malignant mesothelioma, it is important to know how to get diagnosed and what to do if you are confirmed to have the disease. For more information contact the Patient Advocates at Mesothelioma.net at 1-800-692-8608.

Written by Terri Oppenheimer

Terri Heimann Oppenheimer is the head writer of our Mesothelioma.net news blog. She graduated from the College of William and Mary with a degree in English. Terri believes that knowledge is power and she is committed to sharing news about the impact of mesothelioma, the latest research and medical breakthroughs, and victims’ stories.

Learn more about and contact Terri