Numerous retrospective studies, however, have suggested strongly that the addition of postoperative radiation to incomplete resections improves both progression-free survival (i.e. prevents tumor recurrence) and improves overall survival.In the case of a  grade III meningioma, the current standard of care involves postoperative radiation treatment regardless of the degree of surgical resection. This is due to the proportionally higher rate of local recurrence for these higher-grade tumors. Grade II tumors may behave variably and there is no standard of whether to give radiotherapy following a gross total resection. Subtotally resected grade II tumors should be radiated. Chemotherapy
Likely, current chemotherapies are not effective. Antiprogestin agents have been used, but with variable results. A 2007 study of whether hydroxyurea has the capacity to shrink unresectable or recurrent meningiomata is being further evaluated. Epidemiology
Many individuals have meningiomata, but remain asymptomatic, so the meningiomata are discovered during an autopsy. One to two percent of all autopsies reveal meningiomata that were unknown to the individuals during their lifetime, since there were never any symptoms. In the 1970s, tumors causing symptoms were discovered in 2 out of 100,000 people, while tumors discovered without causing symptoms occurred in 5.7 out of 100,000, for a total incidence of 7.7/100,000. With the advent of modern sophisticated imaging systems such as CT scans, the discovery of asymptomatic meningiomata has tripled.Meningiomata are more likely to appear in women than men, though when they appear in men, they are more likely to be malignant.
Primitive neuroectodermal tumor is a malignant (cancerous) neural crest tumor. It is a rare tumor, usually occurring in children and young adults under 25 years of age. The overall 5 year survival rate is about 53%.It gets its name because the majority of the cells in the tumor are derived from neuroectoderm, but have not developed and differentiated in the way a normal neuron would, and so the cells appear "primitive".PNET belongs to the Ewing family of tumors. Genetics
Using gene transfer of SV40 large T-antigen in neuronal precursor cells of rats, a brain tumor model was established. The PNETs were histologically indistinguishable from the human counterparts and have been used to identify new genes involved in human brain tumor carcinogenesis. The model was used to confirm p53 as one of the genes involved in human medulloblastomas, but since only about 10% of the human tumors showed mutations in that gene, the model can be used to identify the other binding partners of SV40 Large T- antigen, other than p53. Diagnosis
Classification
It is classified into two types, based on location in the body: peripheral PNET and CNS PNET. Peripheral PNET
The peripheral PNET (pPNET) is now thought to be virtually identical to Ewing sarcoma:
"Current evidence indicates that both Ewings sarcoma and PNET have a similar neural phenotype and, because they share an identical chromosome translocation, they should be viewed as the same tumor, differing only in their degree of neural differentiation.