[Comparative study of three different decalcifying solutions in bone metastasis specimens with breast cancer]

Objective: To investigate the optimal strategy for immunohistochemical (IHC) staining in bone metastasis specimens from breast cancer. Methods: Twenty-eight bone metastases specimens from breast cancers were divided into three groups and subjected to different decalcifying agents (group A-10% nitrate, group B-EDTA decalcification, and group C-imported decalcifying solution RapidCal). The effects of those on HE and IHC staining for Ki-67, ER, PR, GATA3, RANK, RANKL, HER2 and HER2 FISH results were assessed. Results: There were no significant differences among three groups in HE morphology and IHC staining. Antigen content in the RapidCal group were all intact; the EDTA group showed a similar staining rate, which was better than the nitrate group (P<0.05). Nitrate group showed marked reduction in nuclear Ki-67 staining, but the loss of cytoplasmic antigens (RANK, RANKL) was less than cell membrane antigen (HER2). For FISH, the RapidCal group and EDTA group showed same results, concordant with IHC staining results. The expression of HER2 protein in the nitric acid group was significantly decreased and chromosome 17 labelling was lost (P<0.05). Conclusions: RapidCal treated bone metastases specimens from breast cancer show excellent sample quality in morphological, IHC and FISH results compared with traditional decalcifying agents. Owing to the longer time of EDTA decalcification, the new decalcifying agent RapidCal plays an important role in quality control and clinical application.