**2. Epidemiology**

#### **2.1. Incidence**

Generally it is recognized that medulloblastoma is the most common malignant brain tumor in children. However, recent data shows that as a group, high-grade gliomas are marginally more prevalent. Approximately 350 new pediatric cases of medulloblastoma are diagnosed in the United States every year and that represents about 30% of pediatric brain tumors and 7–10% of all brain tumors [2, 6, 8, 9, 21–23].

#### **2.2. Age**

There are characteristic bimodal peaks, having a higher incidence in children between 3 and 4 years of age and between 8 and 10 years of age. About 70% of childhood medulloblastomas occur in this age range of the first decade. However, medulloblastoma has been reported in a 2-week-old infant and a 55-year-old adult [6, 9]. About 1–3% of cases are reported in adults, mostly before the age of 40 years [8, 24, 25].

#### **2.3. Sex**

this subset of tumors to be originating from one of the five pluripotent stem cells, the medulloblast, thought to populate the primitive neural tube [1–5]. It has meanwhile been established that the concept of embryonal cell identified as medulloblast does not exist [6, 7]. Hence the term medulloblastoma that Cushing erroneously coined, which is so strongly concreted to the

Medulloblastomas were considered as one of the most disappointing maladies in neurosurgery until the 1960s as survival was still equally poor as was in the early periods of neurosurgery when posterior fossa tumors were most daunting. Overall, improved diagnostic, surgical, and radiation technologies, newer and more effective chemotherapy regimens have led to dramatically improved patient outcomes with advanced research [8]. Multidisciplinary approach being the keystone of success for this formidable disease, significant clinical challenge still remains because of acute onset, rapid growth, rapid clinical course and early fatal termination leading to great number of morbidity and mortality despite aggressive therapeutic strategies [2, 3, 9, 10]. Survival of medulloblastoma patients have become better over the last few decades nonetheless in patients with relapse, the outcome is still miserable. Long-term survival rates have progressively improved from 22% by 1950s to 85% in 2015 with current approaches [11–14]. This significant development has resulted from combination of systemic chemotherapy and improvement in supportive care measures in addition to the regular treatment with surgery and radiotherapy [15–19]. Advances in genetic profiling with emergence of newer agents and development of newer strategies targeting the key molecular alterations have improved the outcomes further [20]. Efforts to improve survival results, dose reduction or elimination of radiation or trial with less offensive chemotherapeutic agents are going on to standardize the

Generally it is recognized that medulloblastoma is the most common malignant brain tumor in children. However, recent data shows that as a group, high-grade gliomas are marginally more prevalent. Approximately 350 new pediatric cases of medulloblastoma are diagnosed in the United States every year and that represents about 30% of pediatric brain tumors and

There are characteristic bimodal peaks, having a higher incidence in children between 3 and 4 years of age and between 8 and 10 years of age. About 70% of childhood medulloblastomas occur in this age range of the first decade. However, medulloblastoma has been reported in a 2-week-old infant and a 55-year-old adult [6, 9]. About 1–3% of cases are reported in adults,

nomenclature, is actually a misnomer [7].

136 Brain Tumors - An Update

treatment of medulloblastoma.

7–10% of all brain tumors [2, 6, 8, 9, 21–23].

mostly before the age of 40 years [8, 24, 25].

**2. Epidemiology**

**2.1. Incidence**

**2.2. Age**

Curiously enough, Cushing found medulloblastomas to be three times more common in males than females and since then most published reports indicate a continuing male predominance. On an average the male to female ratio is 2:1 [2, 8, 9].

### **2.4. Location**

The typical medulloblastoma develops in the midline of the posterior fossa [9, 25]. Some 70–80% of medulloblastomas have been found in the midcerebellum with or without extension into the lateral cerebellar hemispheres. Medulloblastomas typically arise from the medullary velum and fill the cavity of the fourth ventricle and has the propensity to spread throughout the brain and spine via the cerebrospinal fluid (CSF) and about one third of the cases infiltrate the dorsal brainstem [8, 26].
