If you have been exposed to asbestos and your doctor sees a mesothelioma tumor on your CT scan, it may be a waste of time to do a lung fluid test, too.
Many different types of cancer cause excess lung fluid or pleural effusions. Looking for cancer cells in pleural effusions is one of the ways doctors test for cancers like pleural mesothelioma. This is called effusion cytology.
But a new study says this test may not be very reliable for people with malignant mesothelioma. If other factors point to mesothelioma, they say it makes more sense to skip effusion cytology and go straight to a biopsy.
Mesothelioma Develops in People Exposed to Asbestos
Pleural mesothelioma is a type of lung cancer that develops in people who were exposed to asbestos. It is a difficult cancer to diagnose. Many patients do not have any symptoms until their mesothelioma is advanced.
Mesothelioma diagnosis is a multi-step process. Patients may have imaging scans, blood tests, a biopsy and/or effusion cytology. Doctors will also need to know if they were exposed to asbestos since asbestos is the main cause of mesothelioma.
Many mesothelioma patients die within a year of diagnosis. Researchers are looking for ways to speed up treatment and improve the odds of surviving mesothelioma.
Negative Effusion Test Likely in Certain Mesothelioma Patients
When doctors suspect a pleural cancer like mesothelioma, it is common to test the patient’s lung fluid for cancer cells. But researchers in Glasgow, UK say this might be a waste of time for some suspected mesothelioma patients.
They reviewed the cases of 363 patients who were part of a study on mesothelioma biomarkers. Their goal was to see how valuable effusion cytology really is for these patients.
They found that the lung fluid test was negative for mesothelioma cells in 63 percent of patients.
If a patient was exposed to asbestos and had a visible tumor on the CT scan, fluid cytology was only 19 percent effective in confirming mesothelioma. In many of these cases, the cytology results were not even complete.
Fluid Cytology Not Worth the Time
Since the lung fluid test was negative in most patients who were exposed to asbestos and had a positive CT scan, the researchers suggest it might be better not to waste time doing it. Especially since incomplete results mean the patient needs a biopsy anyway.
“Negative cytology is extremely likely in patients with asbestos exposure and a malignant CT report,” they write.
In these cases, the team says a “Direct-to-LAT” approach might be best. LAT stands for Local Anaesthetic Thoracoscopy. It is a very sensitive but expensive method to remove mesothelioma tumor cells for testing.
If a LAT test confirms that the tumor is pleural mesothelioma, treatment could start right away.
Tsim, S, et al, “Baseline predictors of negative and incomplete pleural cytology in patients with suspected pleural malignancy – Data supporting ‘Direct to LAT’ in selected groups”, July 2019, Lung Cancer, pp. 123-129, https://linkinghub.elsevier.com/retrieve/pii/S0169500219304623