Effective treatment depth of photodynamic therapy after partial debulking of nodular basal cell carcinoma

Tumor debulking before topical photodynamic therapy PDT increases the efficiency, however, this raises question of how much of the residual lesion is actually treated. BCC thickness was measured before and after debulking by ultrasound and related to PDT effectiveness. The debulked material was histologically evaluated, and 30 days after treatment, a 2 mm punch biopsy were performed. The thickness measured by ultrasound before and after debulking ranged from 0.9 to 2.3 mm(mean 1.8±0.4mm) and from 0.5 to 1.9 mm(mean 1.3±0.3mm), respectively. This represents a 30%reduction in lesion thickness(0.6±0.3mm average debulking depth)(p<0.001). Clearance rate was 86%, however, lesions less than 1.4mm thick after debulking had 100% clearance. Obtaining the precise thickness of BCC using ultrasound imaging could allow successful PDT treatment of thicker BCC lesions as long as the post-debulking thickness is <2 mm, with complete clearance being achievable at <1.4 mm, suggesting that the use of ultrasound imaging is a valuable adjunct for the precise use of PDT in nodular BCC.