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In a systematic review of 50-year-old published studies, Johns Hopkins Medicine researchers identified a distinct subtype of primary central nervous system lymphoma (PCNS) that is expected to be excised surgical, suggesting a major change in the way this type of tumor is evaluated and managed.
The treatment of PCNS lymphoma – a rare but aggressive form of brain cancer involving immune system cells fighting infections – has traditionally been biopsy, radiation therapy, and high-dose chemotherapy with methotrexate, but surgical resection has not been successful. did not play the risk of damage to healthy brain tissue.
PCNS lymphoma is a form of non-Hodgkin lymphoma confined to the brain, eyes, spinal cord or tissues covering the brain and spinal cord. It accounts for 1% to 2% of central nervous system tumors, or about 1,400 new cases in the United States each year. It strikes more often the elderly and immunocompromised. Ten-year survival is estimated at 10% -13%.
In a report on their study, published on March 20, 2019, in World Neurosurgery, researchers at the Johns Hopkins University School of Medicine and the Johns Hopkins Kimmel Cancer Treatment Center describe two easily distinguishable PCNS lymphoma subtypes in MRI: one is superficial and localized , it can be considered to eliminate it surgically and the other is deep. and probably not suitable for surgery. They estimate that about 20% of patients have localized tumor type and have the potential to heal with surgery followed by methotrexate treatment.
To see if this was the case, the researchers carried out what they described as a comprehensive and systematic review of PCNS lymphoma studies published between January 1968 and May 2018 on patients who had undergone a biopsy of their tumor or surgery to remove them. They followed treatment, side effects, progression-free survival and overall survival, comparing outcomes and complications of biopsied patients with those who underwent surgical resection.
In total, they identified 1,291 citations and 244 manuscripts, and selected 24 out of 24 for targeted data review. The selected studies included information on 15,280 patients and met certain criteria, such as the involvement of human subjects, including data on at least five patients, reporting primary data, and providing survival data or data. complications on stereotaxic biopsy versus PCNS lymphoma resection.
Of the 24, 15 older, smaller studies, which mainly included retrospective single-institution studies, found no benefit from surgery to remove some or all of the tumor. The most important was a 1990 study that confirmed the benefits of methotrexate, but cited postoperative complications in 4 out of 10 treated patients and concluded that surgical treatment was not recommended.
Nine larger and more recent studies, including a randomized German clinical trial of 526 patients published in 2012, found that surgery was beneficial in some patients, particularly when the tumor was well defined and located in more superficial areas of the brain , and in younger patients.
Since the 2012 study, five other studies have begun to reveal differences between PCNS lymphoma subtypes and a potential role for surgery, according to the study leader, Debraj Mukherjee, MD, MPH , Assistant Professor of Neurosurgery and Director of Neurosurgical Oncology at Johns Hopkins Bayview Medical Center.
"What our study has shown us is that we really should think of PCNS lymphoma as two types of tumors with different treatment methods for everyone," said Mukherjee. "Surgery to remove superficial and localized tumor types does not appear to expose patients to higher risk, but also improves outcomes for these patients, while larger and deeper tumors are not suitable for surgery because of their location near the ventricular system in the brain. "
The researchers say that the identification of two different subtypes of PCNS lymphoma explains the discrepancies between older studies that revealed no overall benefit for surgery and more recent studies. "The oldest trials have never addressed this issue of the size, type and location of the tumor," says Mukherjee. "It was thought that these tumors were all diffuse and multifocal, and too difficult to remove surgically without increased risk to patients."
The researchers are calling for more prospective studies to better define the role of surgery in the treatment of PCNS lymphoma.
In addition to Mukherjee, other researchers were Collin Labak, Matthias Holdhoff, Chetan Bettegowda, Gary Gallia, Michael Lim and Jon Weingart.
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