Germinomas of the brain are among the most radiation-curable of all tumors. The current ¨gold standard” is clearly radiation therapy, delivered to encompass the ventricular system of the brain (NOT the entire brain or the spinal cord, unless the patient has evidence of tumor spread to these regions) with an additional boost of irradiation to the site of the tumor. This approach will produce a cure for the tumor in over 90% of cases of germinoma of the brain. However, in pre-pubertal children, as well as children already presenting with some damage as a consequence of their tumor, even the current standard of radiation therapy treatment alone can produce some impairment of learning abilities, memory and intellectual functions. Accordingly, studies in North America, Europe and Japan in recent years have been trying to reduce the doses of radiation therapy down to a safer level, by giving the radiation therapy after a few courses of chemotherapy. Studies from New York University (Dr Jeffrey Allen) have suggested that such an approach, combining chemotherapy followed by radiation therapy localized only to the tumor site, will result in over a 90% cure rate in select children with localized brain germinomas. At our hospital, we have followed Dr. Allen's suggested approach, but followed by low dose ventricular field irradiation and a small boost to the tumor site –with 100% survival without any relapse of the tumor. Recently, the North American Children's Oncology Group (COG) have opened a national study in which children with germinoma of the brain are randomly assigned to receive either radiation therapy alone (to the ventricular system of the brain plus a boost to the tumor site) or to receive Dr. Allen’s chemotherapy followed by just local field irradiation. Finally, the optimal treatment for those children with the more difficult mixed malignant germ cell tumors of the brain, continues also to be somewhat controversial. These tumors are far less sensitive to chemotherapy than germinomas, and are not cured by radiation therapy alone. The currently accepted treatment approach is to use several cycles of more intensive chemotherapy, followed by radiation therapy. Results from such an approach indicate cure rates of around 60% to 80%. The controversy surrounds how wide a field of radiation therapy needs to be applied. My own studies as well as those from European investigators, would indicate that only high dose radiation therapy directed only to the tumor site, need be employed (with the addition of low doses of irradiation to the ventricular system to “cover” any germinoma component). However, the current national COG trial administers full doses of irradiation to the entire brain and spine to these children – many of whom are prepubertal and therefore at much greater risk for long term toxicities of the radiation therapy. Even the COG Committee is now considering eliminating whole brain and spinal cord irradiation in their next Mixed Malignant Germ Cell Tumor trial, following completion of the present trial. |