Histopathological and immunohistochemical evaluations of breast cancer treated with radiofrequency ablation

Although RF ablation is a promising non-surgical ablation technique for the treatment of breast cancer, assessment of the efficacy requires not only imaging of tumor necrosis but also histological confirmation.

Two series of patients were treated with RF ablation. In the first series, 17 patients underwent surgical resection immediately and 17 underwent delayed mammotome excision in the second series. The ablated tumor tissue was examined histologically with H&E staining and NADH-diaphorase staining. Furthermore, ssDNA was immunohistochemically stained in the specimen where tumor cells were histologically detected.

In the first series, mild response was histologically seen in 14 of 17 patients (82%), whereas complete response was observed in 8 of 16 patients (50%) in the second series. However, NADH-diaphorase staining did not demonstrate any viable tumor tissues in any patient in either the first or the second series. ssDNA staining was positive (non-viable) in 13 of 16 cases in the first series, but it was positive in all 8 cases tested in the second series.

Although NADH-diaphorase staining is essential to evaluate tumor cell viability immediately after RF ablation, ssDNA may be useful for the assessment of cell viability after some interval following RF ablation.