The characteristics of mediastinal neuroblastoma.

The prognosis of mediastinal neuroblastoma has been reported to be better than for other neuroblastomas. The reason for this is however not clear. Furthermore, a comparison between mediastinal neuroblastoma and the other neuroblastomas has been rarely reported so far. In this study, the characteristics of mediastinal neuroblastoma (84 cases) are investigated and compared with those of other neuroblastomas (440 cases). Regarding clinical factors, the age distribution and the rate of cases detected at mass screening were similar in both groups. According to Evan's staging system, the rates of early stage (I, II) were 62% in the mediastinal neuroblastoma and 38% in the other neuroblastomas (p<0.001). Regarding the biological prognostic factors, a favorable histology based on Shimada's classification was found in 100% (35/35) of the mediastinal neuroblastoma cases and in 85% (112/132) of the other neuroblastoma cases (p<0.05). With regard to N-myc amplification, all of the examined 42 cases in mediastinal neuroblastoma had a N-copy number of less than 10 copies, while 32 of the examined 263 cases (12%) in the other neuroblastomas had an amplification of N-myc of more than 10 copies (p<0.05). The 5-year survival rates were 78% in the mediastinal neuroblastoma and 59% in the other neuroblastomas, respectively. Of the cases who underwent an incomplete resection of primary tumors in localized neuroblastoma, the 5-year survival rate of the mediastinal neuroblastoma cases was significantly more favorable than that of the other neuroblastomas. The majority of mediastinal neuroblastoma cases showed an early stage and favorable prognostic factors. It is likely that the clinical and biological prognostic factors of the tumor are therefore more closely correlated with the outcome of mediastinal neuroblastoma rather than the degree of the surgical resection. Regarding the treatment for mediastinal neuroblastoma, it is most important to evaluate the biology of the tumor after surgical resection.