Focal laser interstitial thermotherapy (LITT) at 980 nm for prostate cancer: Treatment feasibility in Dunning R3327-AT2 rat prostate tumour

OBJECTIVE To examine the feasibility and reproducibility of laser interstitial thermotherapy (LITT) as a minimally invasive method for the treatment of prostate cancer. MATERIALS AND METHODS Heterotopic tumours of prostatic adenocarcinoma (Dunning R3327-AT2) were induced in 10 male Copenhagen rats. After preoperative magnetic resonance imaging (MRI), a 10-mm cylindrical diffusing fibre developed by our research department was inserted under ultrasonographic guidanceinto the tumour. LITT was performed with a 980-nm diode laser (power 5 W) for75 s (fluence rate of 1145 J/cm²). Non-enhanced T2-weighted and dynamic gadolinium-enhanced T1-weighted MRI examinations were performed at baseline, 1 and 48 h after the procedure and correlated with histological findings. RESULTS The necrosis lesions induced by LITT were visible on MRI. The mean (SD) ellipsoid necrosis volumes were 0.748 (0.075) mL at 1 h and 0.982 (0.052) mL at 48 h after the LITT procedure, and significantly different (P <0.001). Histological analysis showed a strong correlation (r = 0.87) with the mean necrosis volume obtained by MRI at 48 h after LITT. CONCLUSIONS In a prostatic adenocarcinoma model, 980-nm LITT induces reproducible necrosis volumes. Further characterization of the response to LITT in an animal model and in human tissues will be important in establishing the efficacy of the procedure for prostate cancer focal therapy.