Cuestionario de saberes y prácticas de convivencia en el aula

Progress in the treatm ent of brain tum ours has been relatively p o o r com pared to that achieved in other forms of childhood cancer. This is due in p a rt to the differing tum our types occurring in different areas of the brain and also to the low incidence of these tu m o u rs m aking it difficult for m eaningful therapeutic trials to be conducted (Einlay et al, 1987). Historically the standard approach to the treatm en t of ch ild h o o d brain tu m o u rs has been either surgery alone or surgery follow ed by

surgery and radiotherapy it was often felt there w as no advantage to subjecting the child to u n p ro v en chem otherapeutic agents. P io n eerin g trials in the 1970's led to the use of vincristine and nitrosureas in th e treatm ent of paediatric brain tum ours and also led to the estab lish m en t of m ulticentre co-operative group trials for the testing of a d ju v a n t chem otherapy in the treatm ent of children w ith new ly diagnosed b rain tum ours (Rosenstock et al, 1976; Shapiro, 1975).

Surgery

The m ain aims of surgery are to establish a histological diagnosis, to restore the CSF pathw ay and reduce the tu m o u r b u rd en (Pollack, 1999; Punt, 1995; Tomita, 1998). Craniotom y provides the largest sam ples for pathological exam ination w hereas stereotactic or ventriculoscopic biopsies are less invasive forms of surgery b u t have a low er diagnostic value for heterogeneous tum ours (Tomita, 1998). For exam ple, gliom as originating in the brain stem m ay be a mix of benign and m a lig n a n t astrocytom a therefore a sm all sample of tissue taken from one area of the tu m o u r m ay not be representative of the entire tum our. O btaining m axim um cytoreduction and neural decom pression enhances tu m o u r

sensitivity to adjuvant therapy (either radiotherapy a n d /o r

chem otherapy) - the sm aller the tum our the greater the response to therapy. This also m eans a lower dose of radiation and less aggressive chem otherapy can be used (Tomita, 1998). T um our resection is u su ally accom plished by ultrasonic aspiration, w hich aids internal debulking of the tum our. In m ost tum ours there is no well defined m argin betw een tu m o u r and norm al brain and this infiltration of the s u rro u n d in g brain tissue is the lim itation to complete resection (Pollack, 1999).

The increased use of CT and MRI techniques has allow ed earlier diagnosis of tu m o u rs and have provided the surgeon w ith a better delineation of the location and contours of the tu m o u r and its rela tio n to su rro u n d in g structures, effectively providing a "road m ap" to th e tum our (Finlay et al, 1987). Stereotactic biopsy using the data p ro v id ed by MRI and CT scans has become im portant in the n eu ro su rg ical

m anagem ent of children with brain tum ours. It enables th e pathological diagnosis of lesions w ithin brain structures th at w ere once considered to be inaccessible, such as the brain stem, basal ganglia, hypothalam us and pineal body (Finlay et al, 1987). The stereotactic aspiration of tum ours allows palliative m anagem ent of patients w ith recurrent tum ours and can be repeated if necessary (Finlay et al, 1987).

Surgery is the m ost effective m ode of treatm ent for p rim ary ependym om a. Com plete resection is associated w ith a five year progression free survival (PFS) of 60-80% com pared to 0-30% in patients undergoing incom plete resection (H ukin et al, 1998; Pollack et al, 1995). Incom plete tum our removal is com m on am ong patients w ith 4^ ventricle ependym om a. This is due to the infiltration of tu m o u r along the ventricle into the brain stem. In patients w ith su p ra ten to ria l lesions the degree of resection is dependent u p o n the size and extent of the tum our. Total rem oval of tum our has been reported in u p to 70% of intram edullary ependym om a and 90% of cauda equina tu m o u rs (Kun et al, 1988). In a recent study ten patients w ith ependym om a h a v e been treated w ith total surgical resection and no ad ju v an t therapy. Of these patients only one has experienced a recurrence (Tomita, 1998). A prospective study investigated survival in ten paediatric patients w ith intracranial ependym om a treated by surgery alone. All patients h a d radiologically confirm ed gross total resection. Seven of the ten p atien ts rem ained in rem ission 48 m onths after surgery and three p atien ts u n d erw en t repeat surgical resections for recurrent or residual disease. Seven of the eight supratentorial ependym om a w ere in rem ission 48 m onths after gross total resection (Hukin et al, 1998). Twelve p atien ts w ith supratentorial ependym om a were treated w ith radical surgery alone in an Italian study (Palma et al, 2000). Three of these p atien ts suffered a recurrence, three patients died w ith in 11 m onths of surgery and the rem aining patients w ere in rem ission. This study show ed th a t true radical excision cannot always be achieved in su p ra ten to ria l

w ith radiotherapy a n d /o r chem otherapy for the treatm ent of all grades of ependym om a.

Resection is the treatm ent of choice for patients w ith gliomas. C h ild re n w ith pilocytic astrocytom a w ho have undergone total surgical resection have 10-20 year survival rates of betw een 90 and 100% (Reddy an d Packer, 1999). Three patients w ith pilocytic astrocytom a w ere treated w ith surgery alone and w ere free of disease at a m ean of 37 m o n th s postoperatively (Vinchon et al, 2001). In a study of thirty five c h ild ren w ith low grade gliomas w ho had no postoperative treatm en t after surgical resection the overall survival at ten years w as 97% and 75% of the patients w ere also disease free at ten years (Pollack et al, 1995). Tw enty-four patients w ith glioma u n d erw en t gross total resection. N one of these patients developed a recurrence of their tu m o u r and h a d a ten year survival of 83% (Fisher et al, 2001). Patients w ith b en ig n astrocytom a of the cerebellum have excellent survival if there is n o b rain stem involvem ent. In a study involving 165 patients w ith th is

tu m o u r type w ho u n d erw en t surgical excision and h ad n o

postoperative treatm ent the ten year overall survival w as 100% for patients w ith the cerebellar form and 80% for those patients w ith b rain stem involvem ent (Pencalet et al, 1999).

R eduction of intracranial pressure using steroids and m an n ito l is th e first step in the treatm ent of m alignant astrocytoma. Radical surgical resection of new ly diagnosed anaplastic astrocytom a and GBM in children is a favourable predictor of outcom e if follow ed by radiotherapy and chem otherapy (Finlay and Wisoff, 1999). O ne p a tien t w ith anaplastic astrocytom a was treated w ith surgery alone and died postoperatively. Two patients w ith GBM u n d erw en t surgery follow ed by chem otherapy. One patient died 12 m onths after diagnosis fro m recurrence and the other patient was alive and disease free 64 m o n th s after diagnosis (Vinchon et al, 2001). Three patients w ith GBM and fiv e w ith anaplastic astrocytom a w ere treated w ith surgery alone. M ed ian

survival w as 11 m onths for GBM and 15 m onths for anaplastic astrocytom a (Raco et al, 1997).