Percutaneous ultrasound guided radiofrequency and microwave ablation in the treatment of hepatic metastases. A monocentric initial experience.

AIM: Percutaneous radiofrequency (RFA) and microwave ablation (MWA) are currently the best treatment options forpatients with liver metastases (LM) who cannot undergo a liver resection procedure. Presently, few studies have evaluated theefficacy of tumor ablation in beginner's hands but none at all in hepatic metastasis. Our aim was to report the initial experiencewith ultrasound as a tool to guide tumor ablation in a low volume center with no experience in tumor ablation. MATERIAL AND METHODS: We conducted a retrospective cohort study, on a series of 61 patients who had undergone percutaneous US-guided ablations for 82 LM between 2010 and 2015. Long term outcome predictors were assessed using univariate and multivariate analysis. RESULTS: Complete ablation was achieved in 86.9% of cases (53/61). All MWA sessions (20/20) attained ablation margins >5mm, compared to 79% (49/62) for RFA sessions (p=0.031). Ablation time was significantly shorter for MWA, with a median duration of 10 minutes (range: 6-12) vs. 14 minutes (range: 10-19.5, p=0.003). There was no statistically significant difference in local tumor progression (LTP)-free survival rates between MWA and RFA (p=0.154). On univariate analysis, significant predictors for local recurrence were multiple metastases (p=0.013) and ablation margins <5 mm (p<.001), both retaining significance on multivariate analysis. Significant predictors for distant recurrence on both univariate and multivariate analysis were multiple metastases (p<0.001) and non-colorectal cancer metastases (p<0.05). CONCLUSION: A larger than 5 mm ablation size is critical for local tumor control. We favor the use of MWA due to its ability to achieve ablation in significantlyshorter times with less incomplete ablations.

The accuracy of endorectal ultrasonography and high-resolution magnetic resonance imaging for restaging rectal cancer after neoadjuvant chemoradiotherapy.

AIM: Endorectal ultrasonography (ERUS) and high-resolution Magnetic Resonance Imaging (HR-MRI) are two frequently used techniques for the preoperative staging of rectal cancer to offer proper neoadjuvant or surgical treatment. Because tumor restaging after neoadjuvant therapy using ERUS and HR-MRI remains challenging the aim of this study is to determine which of the two imaging methods used in restaging rectal cancer has the highest accuracy. MATERIAL AND METHODS: We included patients with rectal cancer who underwent ERUS and HR-MRI scans before and after neoadjuvant chemo-radiotherapy (n-CRT). The n-CRT was followed by imagistic restaging at 6 weeks after the last therapy session and by surgical resection. The pathology stage from the surgical sample was compared with the HR-MRI and ERUS restaging. RESULTS: Fifty-four patients underwent n-CRT and 47 were restaged by both ERUS and HR-MRI. ERUS was accurate in tumor restaging after n-CRT in 29 cases (61.7%) and HR-MRI in 32 cases (68%). Regarding lymphatic node status, ERUS was accurate for 34 patients (72.3%) and had an overall rate of over-staging of 12.8% and 14.9% of under-staging. HR-MRI was accurate for 30 patients (63.8%) in restaging the lymph nodes after n-CRT and had an overall rate of over-staging of 25.5% and 10.7% of under-staging. CONCLUSION: Restaging rectal cancer after n-CRT remains difficult because of radiotherapy tissue alteration, which results in low diagnostic accuracy for both methods. KEY WORDS: Endorectal Ultrasonography (ERUS), High-Resolution Magnetic Resonance Imaging (HR-MRI), Neoadjuvant Chemo-Radiotherapy, Rectal Cancer Restaging.