Interstitial photodynamic therapy as salvage treatment for recurrent head and neck cancer

Abstract

Interstitial photodynamic therapy (IPDT) is a technique for applying photodynamic therapy (PDT) to internal tumours using light delivered via fibres inserted percutaneously. This phase I -II study assessed the safety and efficacy of IPDT for patients with persistent or recurrent head and neck cancer unsuitable for further treatment with surgery, radiotherapy or chemotherapy, recruited for 'last hope' salvage treatment. Patients were sensitised with 0.15 mg kg À1 mTHPC (meso-tetrahydroxyphenyl chlorin) 4 days prior to light delivery from fibres inserted directly into the target tumour (20 J per site at 652 nm) under image guidance. In all, 45 patients were treated. Nine achieved a complete response. Five are alive and free of disease 10 -60 months later. Symptomatic relief (mainly for bleeding, pain or tumour debulking) was achieved in a further 24. The median survival (Kaplan -Meier) was 16 months for the 33 responders, but only 2 months for the 12 nonresponders. The only serious complication was a carotid blow out 2 weeks after PDT. No loss of function was detected in nerves encased by treated tumours. Interstitial photodynamic therapy provides worthwhile palliation with few complications and occasional long-term survivors for otherwise untreatable advanced head and neck cancers. It is a treatment option worth adding to those available to integrated head and neck oncology teams.

Peripheral neural cell sensitivity to mTHPC-mediated photodynamic therapy in a 3D in vitro model

“…This observation needs to be followed up by animal studies to explore whether this phenomenon occurs in vivo before its potential for application in the clinical setting can be determined. Importantly, in the animal studies and human cases in which peripheral nerve sparing has been reported, the PDT was applied to the nerve trunk rather than to the ganglia containing the neuronal cell bodies (Ris et al, 1996;Kubler et al, 2003;Lou et al, 2004;Betz et al, 2007). Our in vitro study indicates that neurons might survive PDT directly applied to the ganglia if an appropriate mTHPC concentration and light dose were used, enabling PDT to be applied to areas of the body rich in neuronal cell bodies such as the DRGs without killing the neurons.…”

“…A range of photosensitisers have been developed, some of which have been used clinically for cancer treatment. One such photosensitiser (meta-tetrahydroxyphenyl chlorin (mTHPC) Foscan, Biolitec AG, Jena, Germany) has been reported to be effective in destroying tumour cells, although not causing major damage to the peripheral nerves in experimental models (Kubler et al, 2003) and in clinical practice (Ris et al, 1996;Lou et al, 2004;Betz et al, 2007). It is not yet clear whether this relative nerve sparing is a feature particular to mTHPC or shared with other photosensitisers.…”

Photodynamic therapy for photochemists

“…PDT may be able to provide palliation of the worst symptoms, such as bleeding, pain and airway obstruction without further loss of function, and if the volume of the active tumour is small, it may be able to stabilize the disease progression. For patients in whom all conventional options have failed, PDT is an approved indication using the photosensitizer mTHPC (Foscan) [20].…”

Photodynamic Therapy in Oncology

“…For larger tumors, PDT can be given interstitially [75]. The response rates achieved are similar to those for other therapies, but PDT can also be used in patients who are unfit for further radiotherapy or surgery.…”