Lung fluid tests for malignant mesothelioma are accurate less than half the time according to cancer researchers at Australia’s Royal Melbourne Hospital.
The production of excess lung fluid (pleural effusions) is a common side effect of mesothelioma, as well as a number of other malignant and non-malignant conditions. In mesothelioma patients, this buildup of fluid often leads to breathlessness and chest pain.
Because this fluid can contain cells from a growing tumor, doctors have used lung fluid testing, also known as cytologic analysis, to identify certain types of cancer, including pleural mesothelioma.
But a new study published in the Internal Medicine Journal suggests that, especially with mesothelioma, lung fluid testing is only moderately effective and must be combined with other diagnostic tools to confirm the disease.
“Cytology has good sensitivity and specificity for the diagnosis of adenocarcinoma, but if another tumour type is suspected, particularly mesothelioma, clinicians should be aware of the limitations,” writes lead researcher, Dr. Paula Loveland.
Cytology More Accurate for Lung Cancer Than Mesothelioma
Adenocarcinoma is a type of cancer that forms in mucus glands throughout the body. It is the most common variety of non-small cell lung cancer, a cancer that shares many commonalities with pleural mesothelioma.
But while lung fluid testing was found to be almost 90 percent effective for identifying adenocarcinomas, it correctly identified mesothelioma only about 45 percent of the time. That means that those patients needed additional tests such as CT scanning and biopsy, to confirm their cancer.
Of the 153 cancer cases analysed over a 12-month period, 40 percent were malignant. Forty-four percent of those were lung cancers, 18 percent were mesothelioma cases, 11 percent stemmed from ovarian cancer, and 8 percent resulted from underlying lymphoma.
In cases where excess lung fluid was produced but no malignant cells were found, it was usually because the patient either had heart problems or a benign condition like pneumonia.
Mesothelioma Diagnosis is Multi-Dimensional
Unfortunately, most patients diagnosed with mesothelioma will develop pleural effusions and that fluid will typically play a role in diagnosis. But mesothelioma diagnosis is complex and usually requires several other diagnostic tools to confirm.
In additional to lung fluid testing for cancer cells and biomarkers, suspected mesothelioma patients may also undergo imaging scans, blood tests, and biopsies so that a pathologist can examine the cells under a microscope.
A patient’s history of asbestos exposure is also important in making an accurate diagnosis of mesothelioma, since this cancer is usually caused by asbestos. An estimated 80 percent of mesothelioma cases occur in people with a known history of asbestos exposure.
Loveland, P, et al, “Diagnostic yield of pleural fluid cytology in malignant effusions: an Australian tertiary centre experience”, June 5, 2018, Internal Medicine Journal, Epub ahead of print