• basal cell carcinoma;
  • meta-tetrahydroxyphenylchlorin;
  • photodynamic therapy

Background Photodynamic therapy (PDT) is a convenient and effective method of treating small superficial tumours. New second-generation photosensitizers offer some advantages over first-generation sensitizers such as haematoporphyrin derivatives.

Objectives To define the optimal treatment parameters (drug dose, light dose and time interval) using meta-tetrahydroxyphenylchlorin (mTHPC) as a photosensitizer in patients with multiple basal cell carcinomas (BCCs).

Methods Light of 652 nm (100 mW cm−2) was used for illuminating different tumours (n = 187) with light doses of 5–15 J cm−2. Following an intravenous injection of 0·1 mg kg−1 mTHPC each patient (n = 5) was illuminated on 4 consecutive days. Each day at least three BCCs per patient were treated with PDT.

Results Response evaluation at 6, 12 and 18 months showed maximum responses for illumination with 10 or 15 J cm−2 on days 1 or 2 after injection (86% complete responses). Normal tissue reactions (oedema and erythema) around the treatment site were more severe on day 1 than after longer intervals.

Conclusions mTHPC is a very effective photosensitizer; short illumination times can result in long-term cures with good cosmetic healing and with skin phototoxicity of short duration.