High radiotherapy dose improves prospects for children with brain cancer
Two studies showed that increasing the dose of radiotherapy given to children with an intracranial ependymoma, a form of cancer of the central nervous system, can significantly improve their survival. These were presented at the 3rd ESTRO (European Society for Therapeutic Radiology and Oncology) Forum in Barcelona, Spain.
Malignant ependymoma, which develops in the cells that line the hollow cavities of the brain, is normally treated with a combination of surgery and radiotherapy, sometimes with the addition of chemotherapy. Since 2004 a dose of 59.4 Gy has been recommended for pediatric cases worldwide, as opposed to the lower (54 Gy) dose that was in use previously. These studies found that adding a radiotherapy boost to this can improve outcome yet further in selected cases.
Ependymoma is the third most common brain tumor in children. With surgery and radiation therapy, the overall five-year survival rate is approximately 70%, but individual prognoses differ considerably according to a number of factors that include age, extent of surgery, and radiotherapy technique and dose.
Lorenza Gandola, MD, head of the pediatric radiotherapy unit at the Fondazione IRCCS, Istituto Nazionale dei Tumori, Milan, Italy, described how her team developed an innovative strategy for children who still had measurable intracranial ependymoma after surgery. In addition to the 59.4 Gy radiotherapy dose to the tumor bed, they added a boost of 8 Gy, divided into two fractions, to the tumor residue.
The researchers used a combination of highly sophisticated radiotherapy techniques to deliver the radiation dose directly to the remaining malignant tissue while sparing normal brain tissue as much as possible. Twenty-four eligible children (median age 4.5 years) of the 143 in the Italian project received the radiotherapy boost and 15 of them are still alive without disease progression at a median of 51 months after diagnosis.
"We believe that our research has the potential to improve outcomes in children with poor prognosis ependymoma, and we hope that the SIOP trial will confirm them further to the benefit of such patients," Gandola concluded.
In another presentation, Anne Ducassou, MD, from the Institut Claudius Regaud, IUCT-Oncopole, Toulouse, France, discussed findings from a study of all 177 children treated for ependymoma in France between 2000 and 2013. The children ranged in age from 1 to 23 years, with a median age of 5 years.
The researchers studied the characteristic of their disease as revealed by MRI scans, and specifically in those related to metabolism, for example perfusion (the blood flow created in the tumor), and the diffusion of intercellular water molecules, which also reflects the number of cells in the tumor.
"We wanted to know whether these metabolic characteristics might have a role in the prognosis of local control of disease and in survival, and whether they might also be able to help us predict relapse, where the disease returns or reoccurs after a period of improvement," said Ducassou.
The researchers found that children with localized disease who had been treated with the high radiation dose of 59.4 Gy, in use since 2004, did better than those who had received the lower dose in use until that date. Of the 177 patients included in the study, the estimated overall survival and progression-free survival were 90% and 67% for patients who received a dose above 54 Gy, compared with 79% and 52% for those who received a lower dose.