Photodynamic therapy for mesothelioma

Our plain-English summary of Photodynamic therapy for mesothelioma, by S.M. Hahn, R.P. Smith, J. Friedberg (Current Treatment Options in Oncology, 2001).

The study

• Authors: S.M. Hahn, R.P. Smith, J. Friedberg
• Journal: Current Treatment Options in Oncology
• Published: 2001;2(5):375-83
• Type of article: Review
• Cited by: 13 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Multiple trials of traditional cancer therapies for malignant pleural mesothelioma (including surgery, radiation therapy, and chemotherapy) have not convincingly demonstrated that any one treatment is superior to supportive care alone. Although there have been reports of long-term survivors who were treated with aggressive surgery combined with radiation and aggressive multi-agent chemotherapeutic regimens, these patient populations are highly selected and results cannot be generalized to a larger population. Despite attempts to use aggressive multimodality therapies, disease recurs in most patients. Local failure in particular is a large part of the natural history of mesothelioma, especially after surgery alone. Therefore, one of the major considerations in the development of new treatments is the inclusion of aggressive local therapies. Photodynamic therapy (PDT), a local treatment modality, is being evaluated as an adjuvant therapy to surgical resection. Clinical use of PDT requires the use of a photosensitizing agent and light of a wavelength specific to the absorption characteristics of the sensitizer in the presence of oxygen. The treatment effect of PDT is superficial, mostly because of the limited depth of light absorption in tissues. Therefore, it is theoretically an ideal treatment for tissue surfaces and body cavities after surgical debulking procedures. One theoretical advantage of PDT is that it can be used to treat the lung surface after a pleurectomy; therefore, patients may be treated with a pleurectomy rather than with an extrapleural pneumonectomy. Several studies have evaluated the efficacy of PDT in the treatment of mesothelioma. Clinical studies have not proven convincingly that the use of PDT is superior to the use of other adjuvant therapies or to surgery alone. The advent of newer photosensitizers and improved laser technology has led to a renewed interest in evaluating PDT. Additional studies are necessary to determine the role of PDT in the treatment of mesothelioma.

In plain English

This article was a review and opinion piece by three authors at the University of Pennsylvania on photodynamic therapy (PDT) for malignant pleural mesothelioma. PDT uses a light-sensitive drug that is activated by laser light. Its effect reaches only a few millimeters into tissue, so it was being tested after surgery that removes visible tumor. The authors described three such drugs (Photofrin, Foscan and lutetium texaphyrin) and their own lung-sparing surgical method, and they summarized earlier studies by other researchers. In the only randomized phase III trial they cited (Pass et al.), median survival was 14.1 months with PDT and 14.4 months without, and that trial showed no survival or local control benefit from adding PDT. In two small Foscan pilot studies (eight and five patients), most patients had no local recurrence for some months. A phase I study of 37 patients at the University of Pennsylvania found that Foscan-based PDT with surgery appeared feasible and tolerable. The authors concluded that PDT had not been convincingly shown to be better than other added treatments or surgery alone, and that more studies were needed. The article did not study asbestos exposure.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Review and opinion article on photodynamic therapy for mesothelioma, summarizing published clinical and preclinical studies and describing the authors' surgical technique
• Who was studied: No study population of its own. The article reviewed clinical studies of PDT in patients with malignant pleural mesothelioma, along with some preclinical mouse studies.
• Exposure: Not an asbestos exposure study; asbestos is mentioned only as background. The treatment reviewed was photodynamic therapy (a photosensitizing drug such as Photofrin, Foscan or lutetium texaphyrin, activated by laser light) given during surgery to remove tumor.
• Main results:
  • In the randomized phase III trial by Pass et al. that the authors cited, median survival was 14.1 months with PDT versus 14.4 months without PDT. Median recurrence-free survival was 8.5 months in the PDT group and 7.7 months in the non-PDT group. That trial showed no survival or local control benefit from adding PDT to debulking surgery.
  • In the 1998 update of the Takita et al. phase II study that the authors cited, patients with stage I and stage II disease (n=13) had a median survival of 36 months and a 61% 2-year survival. Patients with stage III and stage IV disease (n=24) had a median survival of 10 months, and none were alive at 2 years.
  • In the Pass et al. phase I trial of 42 patients that the authors cited, the maximally tolerated dose was 30 J/cm2 of 630 nm light, given 24 hours after Photofrin II at 2.0 mg/kg.
  • In the Ris et al. Foscan pilot study of eight patients that the authors cited, one patient died of contralateral pneumonia 6 days after surgery. The other seven had local control on CT scan but developed distant metastases or contralateral disease 4 to 18 months after the procedure.
  • In the Baas et al. Foscan pilot study of five patients that the authors cited, four were alive with no evidence of recurrent disease 9 to 11 months after treatment.
  • A phase I study of Foscan-mediated PDT in 37 malignant mesothelioma patients at the University of Pennsylvania found that the treatment combined with surgery appeared feasible and tolerable. The article gives no detailed figures.
• The authors' conclusion: The authors concluded that clinical studies had not convincingly shown PDT to be superior to other adjuvant therapies or to surgery alone. They added that newer photosensitizers and lasers had renewed interest in PDT and that additional studies were needed to determine its role.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma.

Medical terms in this study, explained in our Lexicon: Mesothelioma, Pleural Mesothelioma, Chemotherapy, Adjuvant Therapy, Surgical Resection, Extrapleural Pneumonectomy (EPP).

Related studies

• Photodynamic therapy and the evolution of a lung-sparing surgical treatment for mesothelioma — J.S. Friedberg, R. Mick, et al. (2011)
• Radical pleurectomy and intraoperative photodynamic therapy for malignant pleural mesothelioma — J.S. Friedberg, M.J. Culligan, et al. (2012)
• A Novel Prospective Study Assessing the Combination of Photodynamic Therapy and Proton Radiation Therapy: Safety and Outcomes When Treating Malignant Pleural Mesothelioma — S.R. Rice, Y.R. Li, et al. (2019)
• Photodynamic therapy for malignant pleural mesothelioma: the future of treatment? — J.S. Friedberg (2011)
• Phase III randomized trial of surgery with or without intraoperative photodynamic therapy and postoperative immunochemotherapy for malignant pleural mesothelioma — H.I. Pass, B.K. Temeck, et al. (1997)
• Photodynamic therapy for lung cancer and malignant pleural mesothelioma — C.B. Simone, K.A. Cengel (2014)

Browse more research in Current Treatment Options in Oncology, or return to medical research.