Post-therapy damage can look like new brain tumors on MRI


Irradiation and high-dose chemotherapy used to treat two types of brain tumors–medulloblastoma and supratentorial PNET–can cause changes in the brain’s white matter that look like tumors when seen on MRI scans. White matter is the part of the brain composed of nerves that are covered in a pearly-white sheath. Much of the cerebral cortex, where high level thinking occurs, is made of white matter.

From St. Jude Children’s Research Hospital :

Post-therapy damage in medulloblastoma patients can be mistaken for new tumors

St. Jude scientists find that radiation and high-dose chemotherapy damage is usually transient but can mimic cancer and prompt needless additional treatment

Irradiation and high-dose chemotherapy used to treat two types of brain tumors–medulloblastoma and supratentorial PNET–can cause changes in the brain’s white matter that look like tumors when seen on MRI scans. This finding, by a team of investigators led by St. Jude Children’s Research Hospital, is published in the Nov. 15 issue of Journal of Clinical Oncology (JCO).

White matter is the part of the brain composed of nerves that are covered in a pearly-white sheath. Much of the cerebral cortex, where high level thinking occurs, is made of white matter.

The study demonstrates that this damage, called white matter lesions (WMLs), can be mistaken for recurrent cancer, prompting physicians to treat the patient aggressively–and needlessly–with more radiation and chemotherapy.

”Irradiation and high-dose chemotherapy are treatments we want to use as sparingly as possible,” said Amar Gajjar, M.D., member of Hematology-Oncology and director of Neuro-oncology at St. Jude. ”This new information represents an important caution sign for physicians who otherwise might assume that WMLs are actually tumors that need further treatment.”

Gajjar is senior author of the JCO report, which is the first to describe both the finding and the actual incidence of early-onset WMLs–that is, how frequently these lesions occur in patients with medulloblastoma or PNET who have been treated with radiation and high-dose chemotherapy following surgery. The study is also the first to note the impact of such changes in white matter on intellectual outcome in children with brain tumors. Specifically, the study found that the presence of WMLs is associated 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,” says Maryam Fouladi, M.D., assistant member of St. Jude Hematology-Oncology and lead author of the report. ”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.”

The team followed 127 patients for up to 13 months after the start of treatment for brain cancer. During this time 22 of these patients developed WMLs following treatment for brain cancer. The WMLs disappeared in 16 patients (73 percent) within 23.5 months after being detected. In two patients the WMLs remained after 19 and 31 months, respectively. Two other patients developed cancer again while still showing evidence of WMLs. In the remaining patients the WML led to tissue breakdown. Patients with WMLs experienced a significant decline in estimated IQ and math scores.

The researchers concluded that, in patients with medulloblastoma or PNET who had been treated with irradiation and high-dose radiation, WMLs are usually short-lived and do not cause symptoms. However, these WMLs can mimic the early stages of tumor recurrence, and thus make it difficult for physicians to accurately diagnose the return of cancer.

Other authors of this report are Fred Laningham, James W. Langston, Larry E. Kun and Raymond K. Mulhern (St. Jude); Murali Chintagumpala, Charles W. McCluggage, Shaio Woo and Kevin Krull (Texas Children’s Hospital/Baylor College of Medicine, Houston); David Ashley (Royal Children’s Hospital, Melbourne, Australia); and Stewart J. Kellie (Children’s Hospital at Westmead, Sydney, Australia).


One Response to Post-therapy damage can look like new brain tumors on MRI

  1. Anonymous November 20, 2004 at 2:13 am #

    The diagnosis of radiation-induced necrosis is difficult to confirm. Many patients have a mixture of tumor and radiation necrosis and a biopsy may be necessary to distinguish it. Neither symptoms nor radiographic findings clearly distinguish radiation-induced necrosis from tumor. However, the FDG-PET Scan and T1-SPECT studies are useful in differentiating radiation-induced necrosis from recurrent tumor.

    Radiation-induced necrosis is a serious reaction to radiation treatment. It may result from the death of tumor cells and associated reaction in surrounding normal brain or it may result from the necrosis of normal brain tissue surrounding the previously treated metastatic brain tumor. Such reactions tend to occur more frequently in larger lesions, either primary brain tumors or metastatic tumors.

    Hyperbaric Oxygen Therapy (HBO) is now a useful terapeutic option for patients with confirmed symptomatic radiation necrosis. I had an appointment to take my wife to Duke University for Hyperbaric Oxygen Therapy for radiaton-induced necrosis, to reverse the effects, but it was too late, she expired before we could even try. I’ve received a number of emails from radiation necrosis patients who had HBO Therapy, and (the good news is) it works!

    The most common condition treated at some Hyperbaric Oxygen Therapy Centers is tissue injury caused by brain radiation therapy for cancer. Wound healing requires oxygen delivery to the injured tissues. Radiation damaged tissue has lost blood supply and is oxygen deprived. Chronic radiation complications result from scarring and narrowing of the blood vessels within the area which has received the treatment. Hyperbaric Oxygen Therapy provides a better healing environment and leads to the growth of new blood vessels in a process called re-vascularization. It also fights infection by direct bacteriocidal effects. Using hyperbaric treatment protocols, “most” patients with chronic radiation injuries can be cured.

    Hyperbaric oxygen therapy is administered by delivering 100 percent oxygen at pressures greater than atmospheric (sea level) pressure to a patient in an enclosed chamber. Hyperbaric oxygen acts as a drug, eliciting varying levels of response at different treatment depths, durations and dosages, and has been proven effective as adjunctive therapy for specifically indicated conditions.

    Oxygen is a natural gas that is absolutely necessary for life and healing. Purified oxygen is defined as a drug but is the most natural of all drugs. Oxygen under pressure is still the same gas but is more able to penetrate into parts of the body where the arterial flow is hindered, producing ischemia (loss of blood flow) and hypoxia (lack of oxygen). When oxygen under pressure is breathed by a patient in a sealed chamber, it is termed a hyperbaric oxygen treatment (HBOT).

    In addition to raising the arterial levels of oxygen 10 to 15 times higher than that produced by normal atmospheric pressure, the pressure exerted within the body can and does exert therapeutic benefits on acute and chronically traumatized and swollen tissus. The approved course is 2.0 atm (two times above atmospheric pressure) for 90 minutes 20-30 sessions.

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