Purpose:

This study prospectively investigated Protoporphyrin (PpIX) fluorescence as a means of determining the clinical target volume (CTV) necessary to encompass subclinical disease for non-melanotic skin cancers.

Methods and Materials:

PpIX photo-delineation was performed on 30 patients by applying δ-aminolevulinic acid (ALA) or Metvix™ (MAL) cream to the lesions to be treated, in order to delineate a CTV prior to treatment with radiotherapy. This CTV was then compared to conventional margins for subclinical disease (10 mm for poorly demarcated tumors).

Conclusions:

PpIX photo-delineation suggests that conventional 10 mm margins may be inadequately covering areas of subclinical disease in poorly demarcated skin tumors. Longer follow-up may be necessary to determine if this increase in CTV is clinically significant. PpIX photo-delineation also showed a trend for nasal lesions to be multifocal.