該項研究涉及了127例腦癌患者，在接受治療后隨訪了13個月。在這期間，患者中有22例由于治療而出現了腦白質損傷。在檢測到損傷后23.5個月內有16例患者（73％）腦白質損傷消失。有2例患者腦白質損傷分別持續了19個月和31個月。其它2例患者盡管仍然存在腦白質損傷，但是仍然再次形成了腫瘤。其余患者的腦白質損傷導致了組織破壞，出現腦白質損傷的患者的智商測驗和數字計算能力顯著降低。

研究者總結說：小腦幕上原始神經外胚瘤與成神經管細胞瘤的患者接受放療和大劑量化療后，腦白質損傷通常短期存在，并不產生癥狀。但是，腦白質損傷能夠與腫瘤復發的早期階段發生混淆，從而使得醫生很難準確判斷腫瘤是否復發。

MRI May Show Brain Lesions as Tumors
 
High-dose chemotherapy and irradiation used to tread two types of brain tumors--supratentorial primitive neuroectodermal tumor (PNET) and medulloblastoma--can cause alterations in the brain’s white matter that appear like tumors when seen on magnetic resonance imaging (MRI) scans, according to a new study.

The study, conducted by researchers from St. Jude Children’s Research Hospital (Memphis, TN,USA; www.stjude.org), report that this damage, called white matter lesions (WMLs), can be mistaken for recurrent tumors, prompting physicians to treat the patient aggressively--and unnecessarily--with more chemotherapy and radiation.

“Irradiation and high-dose chemotherapy are treatments we want to use as sparingly as possible. This new information represents an important caution sign for physicians who otherwise might assume that WMLs are actually tumors that need further treatment,?said Amar Gajjar, M.D., director of neuro-oncology at St. Jude and senior author of the study, published in the November 15, 2004, issue of the Journal of Clinical Oncology.

WMLs often occur in patients with medulloblastoma or PNET who have been treated with radiation and high-dose chemotherapy following surgery. This research is also the first to observe the effect of these changes in white matter on intellectual outcome in children with brain tumors. Particularly, the study discovered the presence of WMLs is linked with a decline in neurocognitive, or intellectual, function.

“In the vast majority of children, the changes seen on MRI scans after treatment are WMLs and not cancer. Physicians can follow up these initial findings with repeat MRI scans to determine whether the WMLs disappear. If they do disappear, then it wasn’t cancer and didn’t require treatment. But even though these changes tend to be only temporary, some children with these changes tends to develop permanent neurologic problems, such as difficulty swallowing,?said Maryam Fouladi, M.D., from the department of hematology-oncology at St. Jude and lead author of the report.

The study was comprised of 127 patients who were followed for up to 13 months after the initial treatment for brain cancer. During the time, 22 of these patients developed WMLs following the treatment. The WMLs disappeared in 16 patients (73%) within 23.5 months after being detected. In two patients the WMLs remained after 19 and 31 months, respectively. Two other patients developed tumors again while still showing evidence of WMLs. In the remaining patients, the WMLs led to tissue breakdown, and patients with WMLs experienced a significant decrease in estimated IQ and math scores.

The investigators concluded that in patients with medulloblastomas or PNET who had been treated with irradiation and high-dose radiation, WMLs are typically short-lived and do not cause symptoms. WMLs, however, can mimic the early stages of tumor recurrence, and therefore make it hard for physicians to effectively diagnose tumor recurrence.