Table 1.

Problems concerning the efficacy limitations of PDT for BCC treatment.

Problem	Consequences and Details	Sections
Clearance	Surgery often preferred, though inferior cosmesis. Not approved in some countries, including USA.	Section 3; Section 7.1.2. Section 3.
Subtypes	Restricted to nonaggressive, low-risk BCC.	Section 3.
Penetration	Even low-risk subtypes limited to thin (≤2mm) lesions. Penetration of prodrug and light decrease with lesion depth.	Section 3. Section 5.1.
PpIX accumulation	Need increased PpIX at deeper levels where penetration is lower. Adjuvant studies to increase PpIX accumulation. Iron chelators to reduce conversion of PpIX to heme. Differentiation promoters to improve PpIX accumulation.	Section 8.3. Section 8.3. Section 8.4.3. Section 8.4.3.

PDT, photodynamic therapy; BCC, basal cell carcinoma; and PpIX, protoporphyrin IX.