Because it is relatively easy to obtain a sample of this fluid with a needle (as opposed to performing a tissue biopsy), it is often used to reveal important information about a patient’s mesothelioma tumor.
But a new study out of The Netherlands suggests that the practice of using pleural effusions as a substitute for mesothelioma tumor tissue has some serious limitations when it comes to planning immunotherapy treatment.
Immunotherapy for Mesothelioma
Immunotherapy is the process of harnessing the power of the body’s own defense system to fight mesothelioma. One of the strengths of immunotherapy as a mesothelioma treatment is the fact that it is tailored to the immunological profile of an individual’s tumor.
In order to plan immunotherapy, doctors must first evaluate the tumor profile. But researchers at Erasmus MC Cancer Institute in The Netherlands say the practice of using pleural fluid to help do this has drawbacks.
Using a process called thoracentesis they drew off a sample of malignant pleural effusions with a large needle from each patient. At the same time, they also obtained a tissue sample from each patient’s mesothelioma tumor. When they compared the number and types of immune system cells present in each sample, they found that the two types of samples did not always mirror each other.
“The immune cell composition of pleural effusion does not automatically reflect the properties of tumor tissue,” concludes lead author Lysanne Lievense.
A Dynamic Cellular Profile
As the study subjects underwent mesothelioma therapy and had new thoracenteses, the gaps between the immunological makeup of their pleural effusions and their tumor samples were found to get even wider.
“These dynamics could in part be attributed to the treatment regimen consisting of standard chemotherapy and dendritic cell (DC)-based immunotherapy,” writes Dr. Lievense.
As a result, the Dutch group cautions doctors who treat mesothelioma not to place too much stock in pleural effusions testing alone when planning immunotherapy. “This has major consequences when applying precision immunotherapy based on PE findings in patients,” says Dr. Lievense.
The report appears in the journal Lung Cancer.
Lievense, LA, et al, “Precision immunotherapy; dynamics in the cellular profile of pleural effusions in malignant mesothelioma patients”, April 27, 2016, Lung Cancer, Epub ahead of print