Laserinduzierte interstitielle Thermotherapie (LITT) von Lebermetastasen unterschiedlicher Größe im Kleintiermodell

PURPOSE: To assess the effect of laser-induced thermotherapy (LITT) on liver metastases of various size from colon carcinoma in an animal model. MATERIALS AND METHODS: Liver metastases were implanted in 20 Wistar Albino Glaxo (WAG) rats by subcapsular injection of cells from a colorectal strain (CC531) (day 0). The animals were divided into two groups with regard to the measured tumor size of 0.05 - 0.06 cm (3) (group A) and 0.10 - 0.12 cm (3) (group B). On day 14 after laparotomy, the tumors were exposed to 1064 nm Nd:YAG laser light at 2 watts for 5 minutes after intratumoral placement of the laser applicator set. The tumor volumes before (V1, at day 13) and after treatment (V2, at day 28) were determined by MRI and the mean tumor growth ratio (V2/V1) was calculated. RESULTS: The mean tumor volumes V1 and V2 were 0.05 +/- 0.003 cm (3) and 0.23 +/- 0.016 cm (3) in group A, and 0.11 +/- 0.006 cm (3) and 0.68 +/- 0.037 cm (3) in group B. The mean tumor growth ratio (V2/V1) was 4.31 +/- 0.19 in group A and 6.11 +/- 0.14 in group B. The mean volume of the induced necrosis (0.15 +/- 0.01 cm (3)) was the same for both groups ( p > 0.05). Compared to group B, liver metastases of group A showed a significant slower tumor growth velocity (paired t-test, p < 0.0001). CONCLUSION: The interventional treatment of large hepatic tumors with LITT leads to faster tumor growth compared to smaller lesions.