Mesothelin Still Beats Fibulin-3 as Mesothelioma Biomarker

The best biomarker for telling whether pleural effusions mean you’ve got mesothelioma continues to be soluble mesothelin, according to fresh research from Australia.

Mesothelioma diagnosis experts had been hoping that another biomarker — fibulin-3 — might prove even better than mesothelin when it comes to cancer-detection from little more than an effusion sample.

That hope has diminished a bit now that researchers from the University of Western Australia are reporting the results of a comparison they conducted between mesothelin and fibulin-3 as mesothelioma diagnostic biomarkers.

However, while fibulin-3 might not be better at detecting mesothelioma, it turns out that it is superior as an indicator of mesothelioma survival, the researchers write in the July online edition of the journal Current Opinions in Pulmonary Medicine.

Pleural Effusions Not Always From Mesothelioma

The interest in these biomarkers stems from the fact that mesothelioma patients seeing a doctor without realizing they have mesothelioma usually suffer from pleural effusions. Usually, but not always.

And it’s because of the “not always” that doctors can’t give you a definitive diagnosis of mesothelioma just because you have pleural effusions — fluid buildup between the lung lining and the chest wall.

Indeed, as the Australian researchers note, pleural effusions could be a sign of almost anything. There are at least 60 different conditions for which pleural effusions are a symptom. Most of those conditions do not involve cancer and are not life-threatening.

As a result, mesothelioma diagnosis experts have long said it would be very advantageous if there were a surer means of telling whether pleural effusions actually do indicate mesothelioma for any given patient.

The thinking is that doctors could start patients right away on mesothelioma treatments if they could be more confident about making the diagnosis with little more to go on than pleural effusions.

The benefit of jumping straight to treatment is that it narrows mesothelioma’s window of opportunity for unopposed growth. Also, it catches the cancer at a stage when knocking it down is easiest.

Relationship Between Fibulin-3 and Mesothelioma

Fibulin-3 is a glycoprotein associated with tumor growth and spread. Scientists believe it aids mesothelioma by a process of phosphorylation of each cell’s epidermal growth factor receptor.

Scientists also believe fibulin-3 is used by mesothelioma cells to help them take in mitogen-activated protein kinase.

No matter how you slice it, the fact is that fibulin-3 is present with mesothelioma and therefore detectable. For that reason, scientists thought fibulin-3 was the biomarker they were looking for.

One year ago, these same Australian researchers performed a more rudimentary comparison of fibulin-3 and mesothelin as biomarkers.

Writing that time in the journal Thorax, they observed then that mesothelin was the more reliable indicator of mesothelioma but that fibulin-3 was the better predictor of mesothelioma survival.

In that earlier study, the Australian team assembled a cohort of 153 patients who suffered from pleural effusions. It turned out that 82 had mesothelioma, 36 had some other type of malignancy, and the remaining 35 had benign effusions.

The fibulin-3 was not as helpful in diagnosing these cases as was the mesothelin. However, the researchers noted that the less fibulin-3 present in the effusion, the longer the survival when the underlying disease turned out to be mesothelioma.

So perhaps it’s not a bad thing that fibulin-3 is less useful than hoped in terms of mesothelioma diagnosis. If they hadn’t tested it against mesothelin, it might have been a long time before anyone figured out what a potentially great prognostic tool fibulin-3 is.