F. Eickmeyer¹, H.J. Schwarzmaier¹, H. Keller¹, Q. Yang², V.U. Fiedler¹; ¹Krefeld/DE, ²Duesseldorf/DE

Purpose
The prognosis of patients with unresectable liver metastases from colorectal cancer is poor although new chemotherapy regimens have been introduced. In this study, we employed laser-induced interstitial thermotherapy (LITT) for local tumor coagulation.

Material and methods
Patients: In total, 85 non-surgical patients (mean age 65 ± 9.2 y; male 54) with metastases of colorectal cancer were treated by interstitial laser irradiation between 1998 and 2006. All patients suffered from between one and five liver metastases (not larger than 5 cm in maximum diameter). Methods: Laser irradiation was performed using Nd:YAG lasers (λ=1064 nm, cw). The light was transmitted via 1 - 5 internally cooled light guides ending in an optical diffusing tip which was positioned in the centre of the tumor. Laser therapy was guided by MR-imaging (SIGNA SP/i, General Electric, Milwaukee, WI, U.S.A.). For targeting, the built-in localization system (Flashpoint 3000, IGT, Boulder, CO) was used. Follow-up MR examinations exhibited a defined necrosis within the irradiated tissue volumes. Survival rates were calculated using the Kaplan-Meier method.

Results
Results: There was one procedure related death (lethality 1.1 % ). The mean survival of all treated patients was 3.3 ± 0.25 years (CI: 2.8, 3.8) starting the calculation at the date of the diagnosis of the metastases. The mean survival after LITT was 2.6 ± 0.2 years (CI 2.2; 3.0) There was a substantial learning curve. In the first period (1998-2001), the mean survival was 2.2 ± 0.2 years (CI: 1.8, 2.7). Therafter (2001 – 2006), the mean survival increased to 2.9 ± 0.3 years (CI: 2.4, 3.4; p<0.01). In the latter group, the one year survival was 93% and the 3-year survival rate was 56 %.

Conclusion
MR-guided LITT increases the survival in patients with unresectable liver metastases of colorectal carcinoma significanty in comparison with chemotherapy. These data confirm the survival rates reported after interstitial laser coagulation in comparable groups of patients.