Multiple fibre interstitial photodynamic therapy of patients with colorectal liver metastases

Multiple fibre interstitial photodynamic therapy (IPDT) was performed in patients with colorectal hepatic metastases (CRHM) to determine treatment response and side-effects. Ten patients aged 48–75 years with 16 CRHM (seven solitary) were sensitized with (111 mg m−2) haematoporphyrin derivative intravenously. Forty-eight hours later a custom-designed light delivery system guided by ultrasound allowed 630 nm light from a copper vapour pumped-dye laser split into four 200 μm optical fibres to be geometrically positioned within the metastasis. This was performed percutaneously in four patients and at laparotomy in six. Metastases were imaged using computerized tomography and volumes measured by planimetry. Growth was expressed as a ratio relative to the initial volume (RVG). Following IPDT no complications occurred. Three metastases were not treated because of technical problems. No patient suffered skin photosensitivity reactions. Twelve weeks following IPDT, 12 metastases of less than 60 cc initial volume had a mean RVG of 0.99 (s.d. 0.27). One large solitary metastasis continued to grow after IPDT with a RVG of 1.9 after 12 weeks. Untreated hepatic metastases had a mean RVG of 2.13 after 12 weeks. These data suggest that IPDT can reduce the growth of small hepatic metastases and can be performed with low morbidity when applied at laparotomy and with minimally invasive techniques.