PET Imaging of Brain Tumors

The incidence of primary brain tumors is ~ 11:100,000 of the population. In the year 2006, ~ 18,820 new cases of brain and other nervous system tumors were diagnosed in the United States [1] and these tumors were the cause of death in ~ 12,820 patients. Despite advances in diagnosis and therapy, the prognosis for patients with primary brain tumors remains very poor; age-adjusted five-year survival is 30.8 percent. Primary brain tumor is the most prevalent solid tumor in children, and patients 19 years old or younger have a five-year survival of 65 percent. Patients aged 44 or younger have a five-year survival of 58.7 percent. In the elderly, prognosis is extremely poor with a five-year survival of less than 6.5 percent in patients aged 65 and older [1]. The epidemiology of primary brain tumors is extremely complex and includes lesions with both benign and malignant histologies. Between 1985 and 1992, over 60,000 patients diagnosed with primary brain tumors were reported to the National Cancer Data Base (NCDB) [2], and in this group the most frequent tumors were glioblastoma multiforme (GBM) and astrocytoma. The World Health Organization (WHO) has established a four-level classification system (Grade I to IV) with Grade I being most benign, and Grade IV most malignant. The most malignant tumors - astrocytomas and GBM (Grade III to IV) - had overall 30 percent and two percent five-year survival in the NCDB series [2].