Local treatment of colorectal liver metastases: a comparison of interstitial laser photocoagulation (ILP) and percutaneous alcohol injection (PAI).

The purpose of this study was to evaluate the relative merits of two physical methods of locally destroying colorectal liver metastases-interstitial laser photocoagulation (ILP) which causes thermal necrosis, and percutaneous alcohol injection (PAI) which causes cellular dehydration and coagulative necrosis. Seventy-six liver metastases in 22 patients were treated by ILP or PAI. Both techniques were performed using local anaesthesia and intravenous sedation/analgesia. Ultrasound was used to localize the tumours and guide the needles percutaneously. ILP: Up to eight 19 G needles were inserted into the tumour, and down each needle was passed a thin optical fibre; the tumour was heated using low power laser light (2 W) for 500 s from a Nd:YAG or diode laser. PAI: 0.5-1 ml of sterile 95% absolute alcohol was injected into multiple sites of the tumour using a single 19-22 G needle. Dynamic CT scan was used to evaluate the extent of treatment-induced necrosis. Ultrasound showed echogenic changes around the needles/fibre-tips during ILP and PAI; this gave a reasonable guide to the extent of thermal damage for smaller tumours during ILP, but not during PAI. ILP: 54 tumours were treated (median size 2.7 cm). Laser-induced necrosis was clearly seen 24 h after treatment as a well-defined area of non-enhancement on the dynamic CT scan; greater than 50% necrosis of tumour volume was achieved in 87% of tumours (complete necrosis was found in 52% of tumours). PAI: 22 tumours were treated (median size 1.5 cm). Dynamic CT showed patchy areas of non-enhancement in five tumours, decreased density in seven tumours, and no change in 10 tumours; complete tumour necrosis was never achieved. There were no major complications after ILP or PAI, but pain during treatment was more common and more severe with PAI. ILP is a simple, safe and effective treatment for colorectal liver metastases; PAI is relatively ineffective for these tumours (although it has been shown to be much more effective for small hepatocellular carcinomas).