Nasopharyngeal Cancer: Beating the Odds with PDT
The nasopharynx is the uppermost region of the throat (pharynx), located behind the nose. Cancer originating in this area is referred to as nasopharyngeal carcinoma, or NPC, and this disease tends to be very aggressive. At this time, the therapeutic options for persistent and recurrent NPC have limited efficacy, and the prognosis of these tumors remains dismal, with a significant relapse rate and very poor overall survival.
The light-based therapy known as photodynamic therapy, or PDT, can be an effective way to eliminate any nasopharyngeal cancer cells that remain after surgery or radiotherapy, as reported in a review of the medical literature published in the December 2013 Current Treatments Options in Oncology. PDT uses a light-sensitizing substance or photosensitizer that preferentially accumulates in cancer cells; upon exposure to visible light, the photosensitizer converts the light energy into a chemical reaction that breaks down and ultimately destroys the tumor.
PDT is now increasingly viewed as a favorable treatment option for “terminal” or incurable NPC cases, as confirmed by a case report published in the December 2012 issue of Photodiagnosis and Photodynamic Therapy. This report focused on a patient with recurrent NPT who underwent photodynamic treatment for residual disease after chemotherapy and radiotherapy had failed. Five years after completing PDT, the tumor did not progress and the patient was still in good condition. The researchers speculated that this remarkable success story could be due to the strong anti-cancer immunity stimulated by PDT.
Foscan® is a photosensitizer containing temoporfin that is used in PDT. In October 2001, Foscan was approved in the European Union, Norway, and Iceland for photodynamic treatment of patients with advanced NPT and other forms of head and neck cancer. The treatment is considered palliative because it is assumed that the disease is incurable, and because previous attempts with surgery and chemoradiotherapy had ultimately failed.
Last year, a retrospective study found that Foscan-PDT was an effective way to improve survival and quality of life in patients with recurrent NPT (specifically the type known as oropharyngeal carcinoma) or in the case of a second tumor appearance in a head-and-neck region previously treated with radiation. This study’s findings were reported in the March 2013 issue of the European Archives of Otorhinolaryngology.
In a recent pilot study, researchers sought to evaluate the feasibility of palliative PDT for six cases of advanced, recurrent or persistent NPC. These were patients for whom conventional treatments had already failed, so there were no other treatment options. Several PDT strategies were tried that involved diffferent levels of illunmination in the nasopharynx, and the ENT-Magnetic Navigation System was used to help identify the tumor and its specific orientation within the throat area.
Two patients underwent a photodynamic strategy the researchers referred to as NP-PDT type I. Both patients were still alive and free from all disease at 38 and 71 months following the light-based treatments. The other two treatment strategies resulted in local recurrences; however a patient who had a recurrence and then underwent NP-PDT type I showed a good response and went back into remission. Another patient who had a superficial recurrence and then underwent a follow-up NP-PDT type III treatment was still free from disease at 21 months.
The study’s authors concluded that “NP-PDT is a non-invasive and simple treatment modality that may have an important role in the treatment of selected cases of persistent/recurrent NPC in its early stage, not suitable for a conventional therapeutic protocol.” They recommend coupling NP-PDT with the ENT-MNS strategy in order to obtain more precise light delivery within the tumors of these patients, as reported online ahead-of-print in the February 2014 issue of Photodiagnosis and Photodynamic Therapy.
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Succo G1, Rosso S2, Fadda G3, Fantini M4, Crosetti E5. Salvage photodynamic therapy for recurrent nasopharyngeal carcinoma. Photodiagnosis Photodyn Ther. 2014 Feb 13. [Epub ahead of print]
Stoker SD, van Diessen JN, de Boer JP, Karakullukcu B, Leemans CR, Tan IB. Current treatment options for local residual nasopharyngeal carcinoma. Curr Treat Options Oncol. 2013 Dec;14(4):475-91
Indrasari SR, Timmermans AJ, Wildeman MA, Karakullukcu MB, Herdini C, Hariwiyanto B, Tan IB. Remarkable response to photodynamic therapy in residual T4N0M0 nasopharyngeal carcinoma: a case report. Photodiagnosis Photodyn Ther. 2012 Dec;9(4):319-20
Durbec M, Cosmidis A, Fuchsmann C, Ramade A, Céruse P. Efficacy and safety of photodynamic therapy with temoporfin in curative treatment of recurrent carcinoma of the oral cavity and oropharynx. Eur Arch Otorhinolaryngol. 2013 Mar;270(4):1433-9
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