A histopathological study for evaluation of therapeutic effects of radiofrequency ablation in patients with breast cancer

Purpose To reveal the rate of complete therapeutic effect of radiofrequency ablation (RFA) and its correlation with tumor size by the histopathological examination of surgically resected early breast cancers. Methods For 28 patients who received RFA and subsequent surgical therapies for early breast cancer treatment, the effect of RFA was evaluated by both histopathological examination and nicotinamide adenine dinucleotide (NADH)-diaphorase staining of resected tumor specimens according to the criteria described by Seki et al. (this issue). The correlation of 100% RFA effect with tumor parameters including tumor size and the presence of extensive intraductal component (EIC) was examined. Results The mean size and invasive size of the primary tumors were 2.21 cm (ranging from 0.6 to 5.0 cm) and 1.44 cm (ranging from 0 to 5.0 cm), respectively. By examining hematoxylin-eosin (HE) sections, the effectiveness of RFA was found to be 100% in 16 tumors (57%). However, the effectiveness of RFA was found to be 100% in 22 cases (79%) examined by NADH-diaphorase staining of frozen sections containing part of tumorous and nontumorous tissues. The accuracy of diagnosis of complete RFA effect using NADH-diaphorase staining with reference to HE was 79% (22 of 28) with 100% (16 of 16) sensitivity and 50% (6 of 12) specificity. The rate of 100% RFA effect by HE examination was higher in EIC(-) tumors (13 of 17, 76%) than in EIC(?) tumors (1 of 9, 11%) (P = 0.0022), and was higher in tumors of B1.5 cm (10 of 11, 91%) than in tumors of[1.5 cm (6 of 17, 35%; P = 0.0034). All five tumors of B1.0 cm showed 100% RFA effect, but 3 (27%) of 11 tumors of[1.0 and B2.0 cm and 9 (75%) of 12 tumors of[2.0 cm showed suboptimal RFA effect by HE. Conclusions Tumor size of B1.5 cm, strictly B1.0 cm, could be an indication for RFA if a complete histological therapeutic effect is mandatory