Radiation Therapy Can Cause Pulmonary Artery Thrombosis

A new article published in the American Journal of Roentgenology has found that the imaging findings of in situ pulmonary artery thrombosis (PAT) associated with radiation therapy are different from the imaging findings of acute pulmonary emboli and do not appear to embolize, according to a press release.

Based on the differences in clinical prognosis and management strategies, the study authors said in situ PAT associated with radiation therapy must be distinguished from pulmonary embolism. According to the study, in situ PAT associated with radiation therapy has not previously been described in English literature.

First author Jitesh Ahuja, MD, from the thoracic imaging department at the University of Texas’ MD Anderson Cancer Center, searched the radiology database of a large teaching hospital to identify patients who developed PAT after receiving radiation therapy. He recorded the PAT’s computerized tomography (CT) characteristics, including number, location, appearance of filling defects, and the presence of associated lung fibrosis.

Furthermore, he recorded whether it was in situ, acute, or chronic pulmonary embolism; the time between completion of radiation therapy and development of PAT; the size change of PAT; and any observation of new thrombi and emboli on follow-up imaging.

The study population included 27 patients—19 men and 8 women—with a mean age of 71. The primary malignancy was lung cancer in 22 patients, and 5 patients had mesothelioma. Although most PATs were solitary (93%), nonocclusive (96%), and formed an obtuse angle to the vessel wall (89%), all PATs were eccentric within the involved pulmonary artery and located within the radiation therapy volume, according to the study.

The time from completion of radiation therapy to the initial diagnosis of PAT via a CT scan ranged from 53 to 2522 days, with a mean of 675 days. In all patients, CT findings of radiation-induced lung fibrosis were present in the lung supplied by the affected pulmonary artery.

“On follow-up imaging, none of the patients were observed to have filling defects develop in other parts of the [pulmonary artery], which would have suggested embolization,” the authors wrote.

Although the authors acknowledged that radiation therapy is a key part of multimodality treatment of intrathoracic malignancies, they added that associated cardiovascular complications remain the leading non-cancer-related cause of morbidity and mortality among cancer survivors. They concluded that radiologists should be aware of PAT so that they can facilitate accurate diagnoses and management techniques.

REFERENCE

Pulmonary artery thrombosis a complication of radiation therapy [news release]. EurekAlert; October 9, 2020. https://ekaprdweb01.eurekalert.org/pub_releases/2020-10/arrs-pat100920.php. Accessed January 26, 2021.