Abstract P4-15-05: Long-term outcome of breast cancer patients treated with radiofrequency ablation

Abstract

Abstract Background: Radiofrequency ablation (RFA) is considered to be the most promising non-surgical ablation technique for the treatment of small breast cancer. In feasibility studies, the ablated tumor was surgically removed after RFA, and the tumor cell viability were assessed by histological and/or immunohistological examinations. However, these assessments of tumor viability do not take the place of long-term follow-up in patients treated with RFA alone, because they do not allow for them to be followed up for recurrence after RFA, or to determine if there were any undesirable complications of this procedure. At present, few data are available regarding long-term follow-up of patients treated with this modality. Methods: Since 2005, we have performed RFA and sentinel lymph node (SLN) biopsy in 19 cases with invasive breast cancer less than 2.0 cm in greatest diameter. After SLN biopsy, a primary electrode (seven-array model 70 Starburst needle electrode; RITA Medical Systems, Mountain View, CA) was inserted into the tumor under real-time US guidance. Then, the prongs of the needle electrode were deployed over a distance of 3 cm in all cases, and the RF generator (RITA model 1500) was activated and set to automatic, with power at 20 W, temperature of 95°C, and an ablation time of 15 min. Axillary lymph node dissection (ALND) was performed in patients with positive SLNs. Several months after RFA therapy, the ablated tumor tissue was excised by multiple mammotome biopsy and examined histologically or immunohistochemically with H&E staining, nicotinamide adenine dinucleotide (NADH)-diaphorase staining, and single-stranded (ss) DNA staining. All cases were followed-up after breast radiation and systemic therapies. Results: The mean tumor size based on the ultrasonographic maximum dimension was 1.3 cm (range: 0.5–2.0 cm). Although complete response was histologically confirmed in only 8 cases, NADH-diaphorase and ssDNA staining did not demonstrate any viable tumor cells in any of the ablated lesions. At a mean follow-up of 60 months (follow-up range, 37–82 months), there were no cases of in-breast recurrence, although one patient died due to hepatic metastases. Cosmesis of the conserved breast was excellent or good in all of the cases, but a hard lump was persistent after RFA in half of the cases. Conclusions: The long-term outcome of patients treated with RFA is encouraging with regard to cosmesis and local control. However, a persisted lump can cause patient discomfort, anxiety and fear. Therefore, further studies are needed to establish the optimal technique. Moreover, a prospective study will be required to determine the equivalency in local recurrence rates between the RFA therapy and conventional breast-conserving treatment. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-15-05.