tailieunhanh - CNS AND MISCELLANEOUS INTRACRANIAL AND INTRASPINAL NEOPLASMS

Establishing screening programmes without effective follow-up to treat those with precancerous lesions will result in little or no impact on overall cervical cancer mortality rates. Therefore, regardless of which strategy is selected for screening programmes, special attention must be given to strengthening referral systems and having well defined links to higher levels of health care delivery for tracking women with positive screening results. | CNS AND MISCELLANEOUS INTRACRANIAL AND INTRASPINAL NEOPLASMS ICCC III James G. Gurney Malcolm A. Smith Greta R. Bunin HIGHLIGHTS Incidence The CNS malignancies represented of all malignancies during childhood including adolescence . CNS cancer as a group was the second most frequent malignancy of childhood and the most common of the solid tumors. In the US approximately 2 200 children younger than 20 years of age are diagnosed annually with invasive CNS tumors. Astrocytomas accounted for 52 of CNS malignancies PNET comprised 21 other gliomas 15 and ependymomas an additional 9 Figure . Unlike adults and older children young children have a relatively high occurrence of malignancies in the cerebellum and the brain stem. In fact in children younger than 10 years of age brain stem malignancies were nearly as common as cerebral malignancies and cerebellum malignancies were far more common than cerebral malignancies Figure . The incidence of invasive CNS tumors was higher in males than females and higher among white children than black children Figure . The average annual incidence of CNS cancer varied only slightly by age of diagnosis from infancy per million through age 7 years per million . From age 7 to 10 a 40 drop in the incidence rate to per million was observed. CNS cancer rates were fairly consistent among children aged 11 through 17 years until another substantial decrease occurred at age 18 Figure . The increase in CNS cancer rates in the past two decades has been the subject of numerous reports. One concern is that changes in environmental exposures may be responsible for the increasing incidence rates although epidemiologic evidence to support this hypothesis currently is lacking. An alternative explanation is that improvements in diagnostic technology and case ascertainment may be contributing to the increasing trend. Survival In general children with CNS cancer do not share the favorable prognosis of those with .