Brachytherapy

Brachytherapy is the use of radioactive substances to deliver radiation treatments. The term “brachy” comes from the Greek word for short range. This therapy is contrasted to that given as external beam radiation over a long range.

Since the radioactive substances that are used in these treatments are only effective in the short range, they need to be placed in or very near the target. Hence, for mesothelioma, brachytherapy can be used as an “Intraoperative Radiation Therapy” (IORT). The team of Thoracic Surgeon and Radiation Oncologist are able to measure regions of the chest cavity that have not been able to undergo a full oncologic removal of the mesothelioma with at least one centimeter clear margin. A customized radioactive implant can be made by weaving radioactive seeds into a flexible absorbable mesh. This can then be stitched into place. With coordination, this does not add to the overall operative time. The radiation from a radioactive iodine seed implant is delivered over about three months with some residual radioactivity present for about a year. At present there are no prospective data to support this. A few centers are reviewing their clinical experience retrospectively. More data will be available within the following year.

Memorial Sloan Kettering Cancer Center reported the use of High Dose Rate IORT for patients undergoing either an extrapleural pneumonectomy or pleurectomy decortication for mesothelioma on a prospective study. This study was closed early when it was found that the extra time needed to complete this intraoperative therapy, often in excess of two hours, was correlated with a high level of complications

The current practice at the Brigham and Women’s Hospital is to consider all patients for IORT brachytherapy with an Iodine radioactive implant. Intraoperatively, the margins are assessed by frozen section and if positive or unclear, an implant is given. Various centers in the USA and Europe continue to use IORT with a portable electron beam linear accelerator for various tumors including mesothelioma.

CT scan based dosimetry evaluation shows isodose lines for the implant to allow the Radiation Oncologist to assess success of implant.
The mesh in stitched over the affected area.
Front and back view of the competed mesh. Small surgical clips hold the suture in place.
Radioactive iodine seeds in vicryl suture are stitched into vicryl mesh cut and marked out for the correct size of implant.