title: Use of Protoporphyrin Fluorescence to Determine Clinical Target Volume for Non-melanotic Skin Cancers Treated with Primary Radiotherapy.
abstract: OBJECTIVE
  Non-melanotic skin cancers remain the most commonly diagnosed cancers. Radiotherapy and surgery are the most common treatment options. Radiotherapy has a recurrence rate of up to 20% for basal or squamous cell cancers. One of the difficulties is to determine the extent of disease for poorly demarcated tumors. This study utilizes protoporphyrin (PpIX) fluorescence to provide information on the extent of subclinical disease for poorly demarcated tumors treated with radiotherapy.
  
  
  METHODS
  For 33 patients, PpIX photo-delineation was used to determine the clinical target volume (CTV2), which was compared to current conventional margins used to account for microscopic disease.
  
  
  RESULTS
  The use of PpIX photo-delineation demonstrated a significantly larger CTV of 15 mm compared to the conventional 10 mm (p = 0.03) for poorly demarcated lesions. A larger CTV was also demonstrated with PpIX photo-delineation for all basal cell carcinomas (13 mm, p = 0.03) as well as for non-nasal lesions (14 mm, p = 0.04). A trend towards an increased CTV was also noted for squamous cell carcinomas (16 mm, p = 0.19) and nasal primary sites (14 mm, p = 0.11). Nasal primary malignancies had multifocal PpIX uptake in 94% of cases. There was one case of local recurrence and one case of distant recurrence, with an average follow-up time of 22 months.
  
  
  CONCLUSIONS
  The margins currently used to account for subclinical disease may underestimate the extent of microscopic spread for poorly demarcated tumors. Longer follow-up with larger pools of patients are necessary to determine if using PpIX photo-delineation translates into significantly improved clinical outcomes.
authors.affiliation: London Regional Cancer Program, London Health Sciences Center.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Casey
authors.affiliation: Department of Radiation Oncology, Nova Scotia Cancer Center.
authors.forename: Lara
authors.initials: L
authors.lastname: Best
authors.affiliation: Department of Radiation Oncology, London Regional Cancer Program, Western University, London, Ontario, CA.
authors.forename: Olga
authors.initials: O
authors.lastname: Vujovic
authors.affiliation: Physics, London Regional Cancer Program, Western University, London, Ontario, CA ; Department of Medical Biophysics, Western University, London, Ontario, CA.
authors.forename: Kevin
authors.initials: K
authors.lastname: Jordan
authors.affiliation: Department of Radiation Oncology, London Regional Cancer Program, Western University, London, Ontario, CA.
authors.forename: Barbara
authors.initials: B
authors.lastname: Fisher
authors.affiliation: Department of Physics, London Regional Cancer Program, Western University, London, Ontario, CA.
authors.forename: Deborah
authors.initials: D
authors.lastname: Carey
authors.affiliation: Department of Physics, London Regional Cancer Program, Western University, London, Ontario, CA.
authors.forename: Deborah
authors.initials: D
authors.lastname: Bourdeau
authors.affiliation: Department of Radiation Oncology, London Regional Cancer Program, Western University, London, Ontario, CA ; Schulich School of Medicine & Dentistry, Western University, London, Ontario, CA.
authors.forename: Edward
authors.initials: E
authors.lastname: Yu
keywords: ala (δ-aminolevulinic acid); bcc (basal cell cancer); ctv (clinical target volume); mal (methyl-5-aminolevulinate); photo-delineation; poorly defined skin cancer; protoporphyrin-9 (pp-ix); radiotherapy; scc (squamous cell cancer)