Population-based study of medulloblastoma: outcomes in Alberta from 1975 to 1996.

BACKGROUND: The purpose of this study was to determine incidence, survival rate, and prognostic factors as well as the frequency of Collins' Law Violators (CLVs) in an unselected population of medulloblastoma patients. Collins' Law dictates that 'cure' of a child with a tumor occurs after a period that includes the child's age at diagnosis plus 9 months. METHODS: Using the Alberta Cancer Registry a population-based review identified 49 patients with medulloblastoma (19 adults, 30 children) diagnosed from 1975-96. Pathology was reviewed in all cases. All patients had surgical resection, followed by radiotherapy in 47 patients and chemotherapy in 17. RESULTS: The overall 5-year survival was 50%. There was a trend for the extent of resection to be associated with a longer survival (Long rank test, p < 0.06) but this was not significant. Tumor recurrence occurred a median of 22.4 months (range, 6.4-192.3) after diagnosis and median survival after recurrence was 9.3 months (range, 0.4-64.9). The survival curve did not appear to plateau but was affected by tumor-related deaths in 3 (21.4%) of the 21 long-term survivors diagnosed in childhood. These three patients had recurrences a mean of 11.7 years after diagnosis and are designated as CLVs. CONCLUSIONS: The survival rate in an unselected population of patients with medulloblastoma is poor. Aggressive resection of the tumors prolongs survival. The Collins' Law Violators were relatively common and we suggest this concept be abandoned in medulloblastoma.

Exploitation of astrocytes by glioma cells to facilitate invasiveness: a mechanism involving matrix metalloproteinase-2 and the urokinase-type plasminogen activator-plasmin cascade.

The presence of reactive astrocytes around glioma cells in the CNS suggests the possibility that these two cell types could be interacting. We addressed whether glioma cells use the astrocyte environment to modulate matrix metalloproteinase-2 (MMP-2), a proteolytic enzyme implicated in the invasiveness of glioma cells. We found that astrocytes in culture produce significant amounts of the pro-form of MMP-2 but undetectable levels of active MMP-2. However, after coculture with the U251N glioma line, astrocyte pro-MMP-2 was converted to the active form. The mechanism of pro-MMP-2 activation in glioma-astrocyte coculture was investigated and was found to involve the urokinase-type plasminogen activator (uPA)-plasmin cascade whereby uPA bound to uPA receptor (uPAR), leading to the conversion of plasminogen to plasmin. The latter cleaved pro-MMP-2 to generate its active form. Furthermore, key components (i.e., uPAR, uPA, and pro-MMP-2) were contributed principally by astrocytes, whereas the U251N glioma cells provided plasminogen. In correspondence with this biochemical cascade, the transmigration of U251N cells through Boyden invasion chambers coated with an extracellular matrix barrier was increased significantly in the presence of astrocytes, and this was inhibited by agents that disrupted the uPA-plasmin cascade. Finally, using resected human glioblastoma specimens, we found that tumor cells, but not astrocytes, expressed plasminogen in situ. We conclude that glioma cells exploit their astrocyte environment to activate MMP-2 and that this leads to the increased invasiveness of glioma cells.

Air pollution and brain damage.

Exposure to complex mixtures of air pollutants produces inflammation in the upper and lower respiratory tract. Because the nasal cavity is a common portal of entry, respiratory and olfactory epithelia are vulnerable targets for toxicological damage. This study has evaluated, by light and electron microscopy and immunohistochemical expression of nuclear factor-kappa beta (NF-kappaB) and inducible nitric oxide synthase (iNOS), the olfactory and respiratory nasal mucosae, olfactory bulb, and cortical and subcortical structures from 32 healthy mongrel canine residents in Southwest Metropolitan Mexico City (SWMMC), a highly polluted urban region. Findings were compared to those in 8 dogs from Tlaxcala, a less polluted, control city. In SWMMC dogs, expression of nuclear neuronal NF-kappaB and iNOS in cortical endothelial cells occurred at ages 2 and 4 weeks; subsequent damage included alterations of the blood-brain barrier (BBB), degenerating cortical neurons, apoptotic glial white matter cells, deposition of apolipoprotein E (apoE)-positive lipid droplets in smooth muscle cells and pericytes, nonneuritic plaques, and neurofibrillary tangles. Persistent pulmonary inflammation and deteriorating olfactory and respiratory barriers may play a role in the neuropathology observed in the brains of these highly exposed canines. Neurodegenerative disorders such as Alzheimer's may begin early in life with air pollutants playing a crucial role.

Population-based study of medulloblastoma: outcomes in Alberta from 1975 to 1996

BACKGROUND:The purpose of this study was to determine incidence, survival rate, and prognostic factors as well as the frequency of Collins' Law Violators (CLVs) in an unselected population of medulloblastoma patients. Collins' Law dictates that 'cure' of a child with a tumor occurs after a period that includes the child's age at diagnosis plus 9 months.METHODS:Using the Alberta Cancer Registry a population-based review identified 49 patients with medulloblastoma (19 adults, 30 children) diagnosed from 1975-96. Pathology was reviewed in all cases. All patients had surgical resection, followed by radiotherapy in 47 patients and chemotherapy in 17.RESULTS:The overall 5-year survival was 50%. There was a trend for the extent of resection to be associated with a longer survival (Long rank test, p < 0.06) but this was not significant. Tumor recurrence occurred a median of 22.4 months (range, 6.4-192.3) after diagnosis and median survival after recurrence was 9.3 months (range, 0.4-64.9). The survival curve did not appear to plateau but was affected by tumor-related deaths in 3 (21.4%) of the 21 long-term survivors diagnosed in childhood. These three patients had recurrences a mean of 11.7 years after diagnosis and are designated as CLVs.CONCLUSIONS:The survival rate in an unselected population of patients with medulloblastoma is poor. Aggressive resection of the tumors prolongs survival. The Collins' Law Violators were relatively common and we suggest this concept be abandoned in medulloblastoma(AU)