Blood clots in the lungs detected on computed tomography scans conducted for other purposes, known as incidental pulmonary emboli (IPE) are an increasing complication affecting cancer patients.

While these clots are relatively common, knowledge about prognosis, optimal management, and recurrence risk is scarce.

To better understand the natural course of blood clots and possible treatment outcomes among cancer patients, researchers collected data on 926 cancer patients with IPE from 11 observational studies and ongoing registries. 

The primary aim of the study was to compare risk of clot reoccurrence, major bleeding, and death among cancer patients with IPE who had received anticoagulant treatment versus those who had not.

Following a complete review of the data, investigators noted that the risk of developing a subsequent clot was nearly doubled in cancer patients with IPE who did not receive continued anticoagulant treatment (12%), compared to those that had received treatment either with low-molecular-weight heparins (LMWH; 6.2%) or vitamin K antagonists (VKAs; 6.4%).

Major bleeding complications occurred more frequently in patients who received VKAs (13%) compared to those who received LMWH (3.9%).

Six-month mortality was higher in untreated patients (47%) than in patients treated with LMWH (37%) and VKAs (28%).

These findings suggest that anticoagulant therapy after IPE may reduce the risk of clot recurrence in cancer patients.

“While we previously had no evidentiary basis for anticoagulating cancer patients with incidental pulmonary embolism, this study provides a strong argument for always treating this population to prevent recurrence,” said lead study author Tom van der Hulle, MD, of Leiden University Medical Center in the Netherlands.

“Ideally, our findings should be confirmed in a randomised clinical trial. However, given our current and previous results, we believe that it would be ethically challenging and perhaps unfeasible to design a trial allocating patients with cancer-associated IPE to placebo.”

Source: ASH