Immunohistochemistry staining of tumor sections from A549- transferred SCID mice. (A) Tumor paraffin sections of HBO2-14th date showed zonal inflammatory cells and degenerated cells aggregation in the border of coagulation necrosis. Immunostaining of cleaved-caspase-3 after 14 days of HBOT in HBO2 group (B) and control group (C). Note that, in HBOT group, many cleaved-caspase-3 positive apoptotic cells were located in the border between coagulation necrosis and viable tumor cells. Comparative analysis of necrotic field (D) and cleaved-caspase-3 (E) was quantified from groups of mice. Statistical significance (*P < 0.05, compared with control group) was observed in HBOT group. H-score was defined by immuno intensity multiply by staining percentage (range from 0 to 300). Computer counting software of CellQuant and PatternQuant were used (3DHISTECH, Budapest, Hungary) for quantitation.