Extending Late-Stage Mesothelioma Survival with Light Energy
Thoracic surgeon Dr. Joseph Friedberg and his colleagues identified a subset of patients with pleural mesothelioma who achieved a median overall survival of 7.3 years — an impressive survival compared to the usual one-year prognosis.
The findings, which were published recently in The Annals of Thoracic Surgery, stemmed from a retrospective study that detailed significant progress in the fight against this incurable, asbestos-related cancer.
The study included 73 patients with epithelioid mesothelioma who were treated at the Penn Medicine Abramson Cancer Center, where Friedberg practiced before taking the role of director of the Mesothelioma and Thoracic Oncology Treatment and Research Center at the University of Maryland in 2015.
Among all participants, the median overall survival and disease-free survival was 3.0 and 1.2 years, respectively, almost double the typical prognosis for this disease.
But a subset of 19 patients without lymph node metastases showed a median progression-free and overall survival of 2.3 and 7.3 years, respectively.
“That was not anticipated, but [it’s] very encouraging,” Friedberg told Asbestos.com. “It jumps out at you.”
Photodynamic Therapy Is Just One Adjuvant Option
The results also emphasized the need for the randomized clinical trial currently ongoing at Abramson Cancer Center to determine how much of a role PDT plays in increasing survival times.
PDT, which a few cancer centers administer for mesothelioma, uses light energy to kill the tumor cells and is performed in conjunction with surgery. Prior to surgery, patients are given a drug that makes cells sensitive to certain wavelengths of light.
When the cancer cells are exposed to light, the combination of the drug and light causes a reaction that kills nearby cancer cells without harming healthy cells.
After the surgeon has finished removing all visible tumor cells, and with the chest still open, PDT is used to eliminate any remaining tumor cells left behind after surgery.
“Whether or not the photodynamic therapy contributed to the success is unclear at this point. We don’t know for sure,” he said. “That needs to be studied more to make a determination. More likely, the way you do the surgery is critically important.”
Friedberg does not utilize PDT at the University of Maryland when he performs the same aggressive surgery as he did at UPenn. Instead, he uses a post-surgery hyperthermic povidone-iodine wash of the internal chest cavity before surgical closure.
The intent — eliminating any microscopic tumor cells that surgery missed — is similar to PDT.
“Anecdotally, we’re getting good results with this,” he said. “But whether it really makes a big difference or not, you don’t know for sure. I do know the post-operative care is much easier this way.”
Povidone-iodine is a chemical compound and traditional antiseptic that often is used as a pre-surgical scrub. While it has shown positive results in several clinical trials involving other cancers, it has not been officially studied with mesothelioma.
The hope is that it prevents tumoral seeding, which occurs during surgery and slows any future metastasis.
Lung-Sparing Surgery for Mesothelioma
Friedberg believes that longer patient survival in the study could stem from his refinement of the meticulous P/D surgery, which leaves both lungs intact, as opposed to doing the extrapleural pneumonectomy (EPP), which removes an entire lung.
“These patients can still enjoy a pretty good quality of life after a very big operation,” he said. “I think having both lungs allows them to tolerate more aggressive treatment and contributes to overall survival.”
The selection of only patients with epithelioid mesothelioma also played a role in the study and often determines who is eligible for surgery. Epithelial mesothelioma accounts for 50-70 percent of all mesothelioma cases. It also is the most treatable type.
“I think we’re definitely making progress with this disease, but just not as fast as we’d like to see,” Friedberg said. “Surgery techniques are evolving. Adjuvant therapies, immunotherapies, are making a difference. We’re trying to get closer to making this more of a chronic disease than a uniformly fatal one.”