Biliary structures lead to tumour recurrences after laser-induced interstitial thermotherapy

Background and Objective: Thermal diffusion during laser-induced interstiti al thermotherapy (LITT) has not yet been fully investigated in heterogeneou s tissue architecture such as liver. LITT was performed on rabbit liver tum ours to analyse the role of biliary structures in thermal diffusion. Study Design/Materials and Methods: Twenty-four VX2 tumours were grafted on to 12 rabbit livers. The animals were randomly separated into two groups wh en tumour size reached 8 mm. Thermotherapy was performed by delivering the 830-nm output of a diode laser to the centre of the tumour with a 300-mu m fibre. Irradiation conditions were 1.5 W over 900 sec. On day 7 or 14, the tumours were removed and stained with haematoxylineosin and picrosirius red F3BA (PR). Thermal damage was evaluated by PR and electron microscopic exa minations. Results: Among the treated tumours, recurrences were found both at the peri phery (one on day 7, seven on day 14) and within the treated area (two on d ay 7, two on day 14). All recurrences were located in the vicinity of the b iliary structures, which are frequently spared from thermal injury. Conclusion: Biliary ducts lead to a heat sink, thereby facilitating tumour recurrences. (C) 1999 Wiley-Liss, Inc.