Concerns around so-called ‘next generation’ PDT and sonodynamic therapy
Photodynamic therapy (PDT) is a treatment option for some types of cancer that involves administration of a drug that is activated by light, usually from a laser. This causes cell death. The underlying scientific principles and numerous clinical studies have been published in peer-reviewed literature1 2 3. PDT can be curative. For example, in non-melanoma skin cancers, PDT has less morbidity than cryotherapy and avoids the need for skin grafts in surgical excision of large lesions. Often it is palliative where it can bring welcome symptomatic relief and precious extra months’ quality life to the patient.
PDT has several key attractions: there is minimal loss of normal tissue; PDT can be repeated in the same area as often as required; it can be used after conventional treatments have failed or as a stand-alone treatment in appropriate patients.
There are clinics providing what is sometimes called Next Generation PDT (NGPDT) or sonodynamic therapy (SDT). In general, the treatments provided do not have the necessary scientific rigour that is expected. Often the light is delivered externally and it is claimed that this reaches the tumour but light penetration to internal cancers is insufficient for effective PDT. A critical appraisal of a clinical application of SDT has been published4. This concludes that there is no convincing data that shows that treatment carried out as reported is effective in the treatment of primary tumour and multiple metastases. Without critical safety and efficacy information, it is unjustifiable to test unproven unconventional techniques and substances in patients, particularly those in terminal stages.
PDT can be used effectively in the treatment and care of appropriate cancer patients
The use of so-called NGPDT or SDT cannot be recommended.
Prof Harry Moseley, Hon President British Medical Laser Association; Prof Sam Eljamel, Clinical Director Scottish PDT Centre; Prof Keyvan Moghissi, Clinical Director Yorkshire Laser Centre
References
1 Moghissi K, Dixon K, Stringer M et al. Photofrin PDT for early stage oesophageal cancer: Long term results in 40 patients and literature review. Photodiagnosis and Photodynamic Therapy 2009; 6: 159-66.
2 Allison RR, Sibata C, Gay H. PDT for cancers of the head and neck. Photodiagnosis and Photodynamic Therapy 2009; 6: 1-2.
3 Morton CA, McKenna KE, Rhodes LE et al. Guidelines for topical photodynamic therapy: update. British Journal of Dermatology 2008; 159: 1245-66.
4 Huang Z, Moseley H, Bown S. Rationale of Combined PDT and SDT Modalities for Treating Cancer Patients in Terminal Stage: The Proper Use of Photosensitizer. Integrative Cancer Therapies 2010; 9: 317-9.
