Photodynamic therapy of the oral cavity

The last ten years has seen a surge of interest in the use of PDT in the treatment of head and neck cancer, with more than 30 papers reporting clinical results. Reviewing the literature one finds a wide variety of light doses used (from 50 J.cm2 to 1620 J.cm2) often simply 'depending on the size of the tumour to be treated'. Most authors varied their doses from 100 to 200 J.cm2, but given the very limited effective depth of penetration of laser light at 630 nm, few have used satisfactory imaging techniques to match light delivery to tumour dimensions, for example in deciding which patients to treat using a surface illumination technique only, and which to treat using interstitial fibre insertion, and how far apart and how deep to place these fibres. Until this problem of ensuring adequate light delivery to all extensions of tumour is solved, it is perhaps unfair to compare PDT with conventional accepted treatment modalities. (author). 2 refs., 1 tab