[Examination of somatostatin receptor expression in recurrent childhood medulloblastomas]

Medulloblastoma is the most common malignant pediatric central nervous system tumor. Despite the adequate therapy the tumor often recurs. The primary medulloblastoma expresses somatostatin receptor-2 (SSTR-2), but so far we had no experience about the receptor status in recurrent tumors. The presence of SSTR-2 may have an important role in the early detection and treatment of recurrent medulloblastomas. Our aim was to examine the state of SSTR-2 expression in recurrent childhood medulloblastomas. We examined SSTR-2 expression by immunohistochemistry in primary and recurrent medulloblastoma samples of ten children treated with recurrent medulloblastoma at Semmelweis University, Departments of Pediatrics, between 1998 and 2004. All primary and recurrent tumors have been operated at the National Institute of Neurosurgery. We examined the intensity and the percentage of SSTR-2-positive tumor cells in the primary and recurrent tumor samples. All primary tumors were receptor-positive and SSTR-2 was also expressed in all recurrent medulloblastomas. In our samples the percentage of SSTR-2-positive tumor cells was 30-90%. As a positive in vivo control Octreoscan images were available in two cases. In these cases the results of immunohistochemistry and Octreoscan imaging seemed to correlate. As a conclusion, SSTR-2-positive recurrent tumors can be detected early by Octreoscan imaging, and the presence of SSTR-2 establishes the opportunity of applying somatostatin analogues (octreotide) in the treatment of recurrent childhood medulloblastoma.