Interstitial laser photocoagulation in the treatment of hepatic metastases

Interstitial laser photocoagulation (ILP) causes tumor necrosis with local hyperthermia produced by laser light energy. We treated with US-guided ILP 14 patients (7 men and 7 women; mean age: 67 years) and 20 metastases: 9 of them were <3 cm in max. diameter and 11 were >3 cm (mean diameter: 2.9 cm); 14 metastases were from colon carcinoma, 5 from breast cancer and 1 from lung cancer. ILP was performed with 300 and 600 μm quartz fiberoptic guides advanced in 21-18G Chiba needles and a continuous-wave Nd:YAG laser with 1064 nm wavelength. We used single expositions of 5-6 minutes with an irradiation power of 5 watts and scheduled 3 treatment sessions, performing CT scans and biopsies at the end of each session. The extent of induced necrosis was classified as follows on the basis of CT findings: grade 1 = 100% necrosis; grade 2 = necrosis >50%: grade 3 = necrosis <50%. The average follow-up was 6 months. After the 3 scheduled treatment sessions, CT showed grade 1 necrosis in all the lesions <3 cm in diameter and in 4/9 (44%) lesions >3 cm and grade 2 and 3 necrosis in the remaining cases (necrosis >50% in 95% of the lesions and 92% of the patients). The cytologic findings were in agreement with CT results in all grade 2 and 3 cases, but in one grade 1 necrosis cytology showed residual viable tumor. To conclude, ILP is a safe and well-tolerated procedure. Maximum efficacy was observed in the lesions <3 cm, while lesion volume was markedly reduced in the lesions >3 cm. US is a useful tool in the real-time monitoring of this procedure and CT is the most accurate imaging technique to assess treatment efficacy.