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Management of High Lung Shunts for Y90
Summary
Ripal Gandhi, MD, FSVM, a member of the Miami Cardiac & Vascular Institute physician team, delivered a presentation during Session 2 at the 2023 Symposium on Clinical Interventional Oncology on the management of high lung shunts and their implications in patients undergoing certain procedures. This insightful session covered the potential risks associated with high lung shunts, focusing on radiation-induced lung injury and its impact on patient survival.
Dr. Gandhi began by acknowledging the inevitability of encountering high lung shunts in clinical practice, emphasizing the importance of understanding and managing this phenomenon. He highlighted that excessive radiation to the lungs can lead to radiation-induced lung injury, an issue further compounded by decreased patient survival rates.
The physiology of hepato-pulmonary shunts involves the influence of vascular growth factors in the local tumor environment, particularly in hypervascular tumors like hepatocellular carcinoma (HCC). Dr. Gandhi explained that irregular vascularity facilitates the passage of smaller particles from the liver to the lungs. Traditionally, a lung shunt was considered high if it exceeded 10 to —20%, but contemporary standards, especially for glass and resin radio microspheres, now consider values greater than 30 Gy during a single treatment or a 50 Gy lifetime dose.
Several risk factors contribute to high lung shunts, with HCC being a primary pathology. Factors such as macrovascular invasion, large tumor burden (greater than 50%), and infiltrative disease burden are also significant contributors. While the incidence of radiation-induced lung injury is low, Dr. Gandhi stressed the need for caution, especially in patients with pre-existing pulmonary compromise like chronic obstructive pulmonary disease or prior lung resection.
Symptoms of radiation-induced lung injury typically manifest one to three months after exposure, presenting with shortness of breath, fever, and a non-productive cough. Dr. Gandhi described the classic imaging findings associated with this condition, including a bat wing appearance with consolidation and peripheral sparing.
Treatment strategies for radiation-induced lung injury involve providing symptomatic relief. Steroids, bronchodilators, and pentoxyphylline (Trental) are mentioned as potential options. Dr. Gandhi also touched on systemic therapeutic agents that can predispose patients to radiation pneumonitis, emphasizing the need for a conservative approach in such cases.
Dr. Gandhi discussed various approaches to reduce the lung shunt or dose reduction. Bland or chemoembolization using larger particles and under-embolization, hepatic venous occlusion balloons, embolization of portosystemic shunts, ablating the shunt itself, systemic therapy, and external beam radiation were among the strategies mentioned. Dr. Gandhi also briefly touched on the potential use of low-dose Y90 for reducing lung shunts and the importance of maintaining a tumoricidal dose.
A case example was presented to illustrate the utilization of hepatic venous occlusion balloons in reducing lung shunts, allowing for the safe administration of Y90. Dr. Gandhi concluded by emphasizing that a high lung shunt should not immediately preclude the administration of Y90. Instead, various techniques can be employed to decrease the lung shunt, and careful consideration is required to ensure a therapeutic dose to the tumor.
Dr. Gandhi's presentation provided valuable insights into the challenges posed by high lung shunts, their risk factors, symptoms, and diverse strategies for management. The session underscored the importance of a nuanced approach to ensure both patient safety and effective treatment.
View Dr. Gandhi's Interview for More Here
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