Adjuvant intraoperative photodynamic therapy in experimental colorectal cancer

Abstract

Abstract A reliable animal model for quantitative assessment of local recurrence of colorectal cancer was developed using colo26 tumour in BALB/c mice. The effect of adjuvant intraoperative photodynamic therapy to potentially curative surgery on local recurrence was examined in four study and four control groups. Study groups received 15 mg kg Photofrin (a photosensitizing drug) 24 h before surgery. After ‘curative’ tumour excision, the tumour beds were illuminated with either 630 nm or 510 nm laser light each at 40 and 70 J/cm −2. Controls received surgery only, surgery and Photofrin only or surgery and either 630 nm or 510 nm light. The local recurrence rates at 70 days were 17–33 percent in the study groups compared with 83–100 per cent in the control groups (P < 0·001; log rank test). Photodynamic therapy is capable of reducing local recurrence following potentially curative excision of tumour in this model.