Study Supports Curative Radiation Therapy for Pleural Mesothelioma

A new study out of Turkey supports the idea of using highly targeted radiation therapy for pleural mesothelioma that can’t be treated surgically.

Pleural mesothelioma is a cancer that grows on the membrane around the lungs. The membrane is called the pleura. Like all forms of mesothelioma, it carries a grim prognosis.

But the Turkish researchers say new radiotherapy techniques offer the promise of better outcomes. They compared two types of radiation therapy for pleural mesothelioma. They found that both could be delivered safely and with limited damage to nearby organs. 

Unrectable Pleural Mesothelioma

The first-line treatment for pleural mesothelioma is chemotherapy. Ideally, chemotherapy will help to shrink the pleural mesothelioma. Then doctors can remove most of it surgically. They may try to kill any remaining cancer cells with additional chemotherapy or radiation therapy for pleural mesothelioma. 

But many patients are not candidates for mesothelioma surgery. They may be too sick or frail to undergo an operation. In addition, mesothelioma tumors tend to be irregular in shape, making surgery difficult. They also lie close to critical organs like the heart and lungs.

Radiation therapy for pleural mesothelioma offers a non-invasive alternative. New techniques allow radiation delivery to a targeted area. This lowers the risk of damage to nearby organs. 

Comparing Types of Radiation Therapy for Pleural Mesothelioma

The new Turkish study compared two types of targeted radiation therapy for pleural mesothelioma. 

Volumetric modulated arc therapy (VMAT) is a type of IMRT. It uses photons generated by a medical linear accelerator. It directs small beams of varying intensity at the tumor as the machine moves around the patient. This delivers three dimensional radiation to a small area. 

Helical tomotherapy (HT) also provides radiation therapy for pleural mesothelioma from multiple directions. The patient moves through a donut-shaped machine as a radiation source directs beams at the tumor. HT machines include on-board imaging capabilities. HT takes longer than VMAT.

“HT…provided more homogeneous dose distribution and numerically lower doses received by most OARs [organs at risk],” reports study author Berrin Pehlivan. “But again both rotational techniques were successful in keeping the OAR doses below the universally accepted limits.”

The researchers say the biggest drawback to HT was that it took an average of 7.4 minutes compared to just 2.5 minutes for VMAT treatment. 

A New Way to Treat Pleural Mesothelioma?

Until recently, radiation treatment for pleural mesothelioma focused mostly on symptom relief. But the new study suggests that VMAT and HT could change the prognosis for mesothelioma patients with few options.  

“Considering their poor prognosis, these promising findings may open a potential new window for curative treatment of unresectable malignant pleural mesothelioma patients,” write the researchers. 

The current study focused on the experience of just seven patients. The next step for the potential treatment is a larger clinical trial. 

Source:

Pehlivan, B, et al, “Dosimetric Comparison of Lung-Sparing Radiation Therapy between Volumetric Arc Therapy and Helical Tomotherapy for Unresectable Malignant Pleural Mesothelioma”, December 20, 2019, Biomedical Research International, eCollection, https://www.hindawi.com/journals/bmri/2019/4568958/