Irradiating the tracts through which certain interventions are performed can reduce the risk of metastatic pleural mesothelioma. That word comes from a new study in Singapore.
The pleural form of malignant mesothelioma occurs on the lining around the lungs. Doctors often have to insert tools through the chest wall for diagnosis or treatment. The paths or tracts along which they insert those tools can be the site of new mesothelioma tumors.
But the study shows that timely radiation treatment of those paths may prevent metastatic pleural mesothelioma.
Metastatic Pleural Mesothelioma
Metastasis is when cancer cells move from their original site to another place in the body. A tumor that is contained in one spot is easier to treat or remove. Metastatic pleural mesothelioma is harder to treat. When cancer spreads, the odds of survival go down.
One goal of mesothelioma treatments like chemotherapy and surgery is to keep mesothelioma from spreading. Ironically, some procedures that are necessary to diagnose or treat mesothelioma symptoms can end up promoting metastatic pleural mesothelioma.
Inserting a needle through the chest wall to drain excess chest fluid is an example. Many mesothelioma patients experience a build-up of fluid around the lungs as their cancer grows. Doctors can draw off some of that fluid – and reduce symptoms like shortness of breath – by inserting a needle or catheter through the chest wall.
When the needle or catheter is withdrawn, it may take a few mesothelioma cells with it. These cells can turn into metastatic mesothelioma along that tract. Radiation right after the procedure might help keep this from happening.
Prophylactic Irradiation of Procedure Tracts
Prophylactic irradiation is when doctors use radiation on an area before any tumor has formed there. The goal is to destroy those “seed” cells before they can give rise to metastatic pleural mesothelioma.
To see how well this approach works, researchers in Singapore analyzed five clinical trials on prophylactic irradiation of tracts (PIT). The trials included 737 patients with pleural mesothelioma.
“PIT significantly reduces the occurrence of procedure tract metastases in patients with malignant pleural mesothelioma who had a diagnostic or therapeutic chest wall procedure,” writes investigator Chia Ching Lee of National University of Singapore.
Not everyone agrees with this assessment, though. A 2019 UK study of 375 patients found that PIT did not reduce the incidence of metastatic pleural mesothelioma. In that study, more than 60 percent of patients who had PIT develop radiation dermatitis as a result.
Mesothelioma patients having a procedure that pierces the chest wall may want to explore the pros and cons of prophylactic radiation with their doctor.
Lee, CC, et al, “Prophylactic Irradiation of Tracts in Patients with Malignant Pleural Mesothelioma: A Systematic Review and Meta-analysis of Randomized Trials”, March 3, 2021, Critical Reviews in Oncology and Hematology, Online ahead of print, https://www.sciencedirect.com/science/article/abs/pii/S1040842821000664?via%3Dihub
Bayman, N, et al, “Prophylactic Irradiation of Tracts in Patients With Malignant Pleural Mesothelioma: An Open-Label, Multicenter, Phase III Randomized Trial”, March 2019, Journal of Clinical Oncology, https://ascopubs.org/doi/10.1200/JCO.18.01678