Abstract 1083: Host-tumor immune response for early breast cancer patients treated with radiofrequency ablation therapy

Abstract

Abstract [Background] We demonstrated immune suppression of regulatory T (Treg) cells in preoperative breast cancer (BC) patients at AACR 2011. Last year we also reported at this meeting that Th17 cells might have some potential to control tumor progression in the same cohort. Modern treatment of operable BC consists of breast surgery, drug therapy and radiation therapy. [Aim] To explore new strategy of BC treatment, we conducted a phase II study on radiofrequency ablation (RFA) in early BC between 2009 and 2013. Twenty patients were enrolled. To examine host-tumor immune response under thermal ablation therapy, Treg cells in peripheral blood mononuclear cells (PBMC) and plasma IL-17A were measured. [Patients and methods] Blood samples were collected from 13 patients before RFA and at the time of 1 month after RFA. Treg cells were examined by counting CD4+CD25highCD127low/-cells in PBMC. Plasma IL-17A was measured using cytometric beads array system. Statistical significance was analyzed using Mann-Whitney U-test. [Results] As of November 2013, all patients were free of recurrence. The percentages of Treg cells had no significant change in 13 patients before and after RFA (2.8% versus 2.7% of CD4-positive cells at mean value). In addition, there was no statistical difference in levels of plasma IL-17A before and after RFA (76 pg/ml versus 116 pg/ml at mean level). [Discussion] Unexpectedly, RFA had no favorable immune response in BC patients, because we observed significant decrease in percentages of Treg cells after breast surgery. The reason is that most patients had T1 tumor and Luminal A-like BC. They had lower percentages of Treg cells in comparison to those of tumor-bearing patients reported previously (2.8% versus 4.2%). [Conclusion] RFA is a promising alternative to breast surgery. However, it may make little effect on host-tumor immune response in favorable subtype of early BC. Citation Format: Shigeru Imoto, Noriko Nakatsugawa, Takayuki Ueno, Hiroki Ito, Kentaro Imi, Kaisuke Miyamoto, Manami Kitamura, Hirotsugu Isaka, Tetsuya Nakatsura. Host-tumor immune response for early breast cancer patients treated with radiofrequency ablation therapy. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1083. doi:10.1158/1538-7445.AM2014-1083