Radiotherapy in the treatment of primary central nervous system lymphoma (PCNSL)

Characterizing second line and beyond therapies for primary central nervous system lymphomas

Primary central nervous system (CNS) lymphoma (PCNSL) is a rare and aggressive lymphoma that affects the CNS without other systemic involvement. High-dose methotrexate (HDMTX)-based regimens are recommended frontline treatment, followed by consolidation with either high-dose chemotherapy, whole brain radiation (WBRT) +/- sequential temozolomide (TMZ), or autologous stem cell transplant (autoSCT). Despite advancements with HDMTX and rituximab, up to half of patients will relapse. Treatment for relapsed or refractory (R/R) disease varies widely as preferred regimens are not well-established. Our study aimed to provide real-world characterization of R/R PCNSL therapies. The secondary objective was characterization of consolidation methods after frontline treatment. This retrospective, descriptive analysis included 54 adult PCNSL patients that received a HDMTX-based frontline regimen between 4/1/2016 and 7/1/2022. Patients receiving HDMTX for the purpose of secondary CNS lymphoma, non-B cell origin PCNSL, and intraocular lymphoma were excluded. Thirty-one patients (57%) received consolidation therapy with rituximab and high-dose cytarabine (R-HDAC), WBRT, or both. Thirteen patients (24%) proceeded with autoSCT. Twenty-five patients had disease progression, with 17 patients receiving second line treatment. The second line treatments were WBRT (24%), clinical trial (18%), rituximab with lenalidomide (R2; 18%), re-induction with HDMTX-based regimens (18%), ibrutinib with rituximab (12%) and R-HDAC (12%). Seven patients progressed, and all received third line treatment. Treatments varied, including R2; ibrutinib +/- HDMTX; rituximab, methotrexate, and cytarabine; R-HDAC; R-nivolumab; and WBRT. Five patients received a fourth line regimen of R +/- lenalidomide, R-HDMTX, or nivolumab monotherapy. Regimens used for the three patients who received fifth line treatment and beyond included R-TMZ and pembrolizumab monotherapy in addition to previously described regimens. Regimen selection is varied and highly dependent on physician preference and patient factors, including clinical trial eligibility, prior therapies, performance status, organ function, and treatment intent. Prospective clinical trials are needed to guide optimal management.

Study on primary central nervous system lymphoma in pediatric patients

BACKGROUND

Primary central nervous system lymphoma (PCNSL) in pediatric patients presents diagnostic and treatment challenges, leading to delays and suboptimal strategies. Moreover, PCNSL in immunocompetent pediatric patients is rarely reported. This retrospective study aimed to describe the demographic and clinical features, as well as outcomes, of pediatric PCNSL cases.

METHODS

A retrospective review was conducted on 11 immunocompetent pediatric patients diagnosed with PCNSL between January 2012 and April 2020. Data regarding age, gender, initial presenting symptoms, tumor location, and radiological characteristics were collected. Treatment strategies and analyzed prognosis were documented. Survival curves were generated using the Kaplan-Meir method, and data were analyzed using SPSS (version 23.0, IBM Corp.).

RESULTS

The study cohort comprised 11 patients, including 10 males and 1 female. The age at diagnosis ranged from 4 to 15 years, with a median age of 10.6 years. Headache was the most common presenting symptom, observed in 81.8% (9/11) of patients. Tumor locations in the supratentorial and infratentorial regions exhibited a similar occurrence rate. All tumors showed strong contrast enhancement on T1-weighted images. The average survival time for the 11 patients was 44.4 months. Among them, 5 patients died by the last follow-up visit, with a mean survival time of 8.8 months (one patient died in a car accident).

CONCLUSION

Headache is the predominant manifestation of PCNSL in pediatric patients. PCNSL demonstrates imaging characteristics resembling various intracranial tumors and is associated with a poor prognosis. Therefore, pediatric neurosurgeons should exercise caution in diagnosing and treating intracranial lymphoma.

Treatment of Primary CNS Lymphoma: Maximizing Clinical Benefit, Minimizing Neurotoxicity

PURPOSE OF REVIEW

The optimal treatment for newly diagnosed and refractory or relapsed primary central nervous system lymphoma (PCNSL) is not fully defined. We review the epidemiology, clinical presentation, and current management strategies for newly diagnosed PCNSL as well as emerging treatments for refractory and relapsed disease.

RECENT FINDINGS

In recent decades, the incidence of PCNSL has increased in the elderly population. With advancements in chemotherapy for PCNSL, survival has improved. However, outcomes remain inferior when compared with other forms of extranodal lymphoma. Additionally, treatments can be associated with clinically significant neurotoxicities. Despite advances in the treatment of PCNSL, current treatment regimens remain suboptimal in terms of response rates and neurotoxicity. Well-tolerated agents, especially for the elderly, are still needed.

Lipidic Cubic-Phase Nanoparticles (Cubosomes) Loaded with Doxorubicin and Labeled with 177Lu as a Potential Tool for Combined Chemo and Internal Radiotherapy for Cancers

Lipid liquid-crystalline nanoparticles (cubosomes) were used for the first time as a dual-modality drug delivery system for internal radiotherapy combined with chemotherapy. Monoolein (GMO)-based cubosomes were prepared by loading the anticancer drug, doxorubicin and a commonly used radionuclide, low-energy beta (β⁻)-emitter, ¹⁷⁷Lu. The radionuclide was complexed with a long chain derivative of DOTAGA (DOTAGA-OA). The DOTAGA headgroup of the chelator was exposed to the aqueous channels of the cubosomes, while, concerning OA, the hydrophobic tail was embedded in the nonpolar region of the lipid bilayer matrix, placing the radioactive dopant in a stable manner inside the cubosome. The cubosomes containing doxorubicin and the radionuclide complex increased the cytotoxicity measured by the viability of the treated HeLa cells compared with the effect of single-drug cubosomes containing either the DOX DOTAGA-OA or DOTAGA-OA-¹⁷⁷Lu complex. Multifunctional lipidic nanoparticles encapsulating the chemotherapeutic agent together with appropriately complexed (β⁻) radionuclide are proposed as a potential strategy for effective local therapy of various cancers.

The Impact of Early Corticosteroid Pretreatment Before Initiation of Chemotherapy in Patients With Primary Central Nervous System Lymphoma

BACKGROUND

The optimal timing of corticosteroid (CS) treatment in patients with primary central nervous system (CNS) lymphoma (PCNSL) remains controversial. While poor clinical presentation may justify early treatment with CS, this may ultimately result in reduced concentrations of chemotherapeutic agents via perturbations in the permeability of the blood-brain barrier.

OBJECTIVE

To investigate whether early CS exposure is associated with beneficial outcomes and/or reduced occurrence of adverse events as opposed to delayed/concomitant administration.

METHODS

Herein we performed a retrospective observational analysis using patients that were prospectively entered into a database. All patients whom were admitted to the University Hospital between 2009 and 2015 with newly diagnosed PCNSL were included within our study.

RESULTS

Our cohort included 50 consecutive patients diagnosed with PCNSL; of these, in 30 patients CS administration was initiated prior to chemotherapy (early), whilst in the remaining 20 patients CS administration was initiated concomitantly with their chemotherapeutic regimen (concomitant). Within the early vs concomitant CS administration groups, no significant differences were observed with regard to progression-free survival (PFS) (P = .81), overall survival (OS) (P = .75), or remission (P = .68; odds ratio 0.76 and confidence interval [95%] 0.22-2.71). Critically, the timing of CS initiation was not associated with either PFS (P = .81) or PFS (P = .75).

CONCLUSION

Early CS administration was not associated with a deterioration in response to chemotherapy, PFS, or OS. As such, administration of CS prior to initiation of chemotherapy is both reasonable and safe for patients with newly diagnosed PCNSL.

pH-Controlled Intracellular in Situ Reversible Assembly of a Photothermal Agent for Smart Chemo-Photothermal Synergetic Therapy and ATP Imaging

To advance anti-tumor efficiency and lessen the adverse effect caused by nanodrug residues in the body, a smart nanoagent system is developed and successfully used in intracellular ATP imaging and in vivo chemo-photothermal synergetic therapy. The nanoagent system is facilely prepared using a DNA complex to modify gold nanoparticles (AuNPs). The DNA complex is formed by three oligonucleotides (ATP aptamer, rC-DNA, and rG-DNA). The CG-rich structure in a ternary DNA complex could be exploited for payload of chemotherapeutic medicine doxorubicin (DOX), thus making efficient DOX transport into the tumor site possible. In tumor cells, especially in acidic organelles (e.g., endosome and lysosome), DOX could be rapidly released via the dual stimuli of overexpressed ATP and pH. What is more, the specific recognition of a fluorescently labeled aptamer strand to ATP can achieve the intracellular ATP imaging. pH-controlled reversible folding and unfolding of intermolecular i-motif formed by C-rich strands can lead to intracellular in situ assembly of AuNP aggregates with high photothermal conversion efficiency and promote relatively facile renal clearance of AuNPs through the disassociation of the aggregates in extracellular environments. Experiments in vivo and vitro present feasibility for a synergetic chemo-photothermal therapy. Such an in situ reversible assembly strategy of a chemo-photothermal agent also presents a new paradigm for a smart and highly efficient disease treatment with reduced side effects.

HDMTX-based induction therapy followed by consolidation with conventional systemic chemotherapy and intraventricular therapy (modified Bonn protocol) in primary CNS lymphoma: a monocentric retrospective analysis

Background

To evaluate outcome and toxicity of High-dose methotrexate (HDMTX)-based induction therapy followed by consolidation with conventional systemic chemotherapy and facultative intraventricular therapy (modified Bonn protocol) in patients with primary CNS lymphoma (PCNSL).

Methods

Between 01/2005 and 12/2013 113 patients with newly diagnosed PCNSL presented at our center; 98 of those qualified for HDMTX based chemotherapy, received a modified Bonn protocol and were included in the analysis. The treatment regimen was based on the “Bonn protocol”, but modified by omission of systemic drugs not able to cross the intact blood brain barrier. Intraventricular therapy was postponed until completion of three induction chemotherapy cycles or was replaced by intrathecal liposomal AraC and rituximab was added to induction from 2010 onwards.

Results

Median patient age was 67 years (range 38–83). Complete response/complete response unconfirmed (CR/CRu) was achieved in 59/98 patients (60%), partial response (PR) in 9/98 patients (9%). Twenty-four patients (23%) had progressive disease (PD), 6 (6%) died on therapy. Median progression-free survival (PFS) for all patients was 11.4 months, median overall survival (OS) 29.1 months. A trend to better outcome for intraventricular therapy versus intrathecal liposomal AraC was found in patients < 65 years (HR 0.53 [0.19–1.47] for OS and 0.46 [0.21–1.02] for PFS. Ommaya reservoir infection occurred in 3/33 patients (9%).

Conclusions

The data of this single center experience suggest that the outcome with a modified Bonn protocol was comparable to that of the previous regimen, showed fewer Ommaya reservoir infections and may have a trend for better outcome with intraventricular therapy.

Electronic supplementary material

The online version of this article (10.1186/s42466-019-0024-2) contains supplementary material, which is available to authorized users.

Terminal Deoxynucleotidyl Transferase-Catalyzed Preparation of pH-Responsive DNA Nanocarriers for Tumor-Targeted Drug Delivery and Therapy

Developing a highly efficient carrier for tumor-targeted delivery and site-specific release of anticancer drugs is a good way to overcome the side effects of traditional cancer chemotherapy. Benefiting from the nontoxic and biocompatible characteristics, DNA-based drug carriers have attracted increasing attention. Herein, we reported a novel and readily manipulated strategy to construct spherical DNA nanocarriers. In this strategy, terminal deoxynucleotidyl transferase (TdT)-catalyzed DNA extension reaction is used to prepare a thick DNA layer on a gold nanoparticle (AuNP) surface by extending long poly(C) sequences from DNA primers immobilized on AuNPs. The poly(C) extension products can then hybridize with G-rich oligonucleotides to give CG-rich DNA duplexes (for loading anticancer drug doxorubicin, Dox) and multiple AS1411 aptamers. Via synergic recognition of multiple aptamer units to nucleolin proteins, biomarker of malignant tumors, Dox-loaded DNA carrier can be efficiently internalized in cancer cells and achieve burst release of drugs in acidic organelles because of i-motif formation-induced DNA duplex destruction. An as-prepared pH-responsive drug carrier was demonstrated to be promising for highly efficient delivery of Dox and selective killing of cancer cells in both in vitro and in vivo experiments, thus showing a huge potential in anticancer therapy.

The Diagnosis and Treatment of Primary CNS Lymphoma

BACKGROUND

Primary central nervous system lymphoma is a diffuse large B-celllymphoma with exclusive manifestation in the central nervous system (CNS), leptomeninges, and eyes. Its incidence is 0.5 per 100 000 persons per year.Currently, no evidence-based standard of care exists.

METHODS

This review is based on pertinent publications (2000-2017) retrieved by aselective search in PubMed.

RESULTS

The clinical and neuroradiological presentation of primary CNS lymphoma isoften nonspecific, and histopathological confirmation is obligatory. The disease, if left un- treated, leads to death within weeks or months. If the patient's general condition permits, treatment should consist of a high-dose chemotherapy based on methotrexate (HD- MTX) combined with rituximab and other cytostatic drugs that penetrate the blood-brain barrier. Long-term survival can be achieved in patients under age 70 by adding non- myeloablative consolidation chemotherapy or high-dose chemotherapy with autologous stem cell transplantation (HD-AST) to the induction therapy. Clinical trials comparing the efficacy and toxicity of these two treatment strategies are currently underway. Con- solidation whole-brain radiotherapy is associated with the risk of severe neurotoxicity and should be reserved for patients who do not qualify for systemic treatment. Some 30% of patients are refractory to primary treatment, and at least 50% relapse. In patients who are still in good general condition, relapse can be managed with HD-AST. Re- exposure to conventional HD-MTX-based polychemotherapy is another option, if the initial response was durable. The 5-year survival rate of all treated patients is 31%,according to registry data.

CONCLUSION

Current recommendations for the treatment of primary CNS lymphomaare based on only a small number of prospective clinical trials. Patients with this disease should be treated by interdisciplinary teams in experienced centers, andpreferably as part of a controlled trial.

Radiation therapy for older patients with brain tumors

The incidence of brain tumors in the elderly population has increased over the last few decades. Current treatment includes surgery, radiotherapy and chemotherapy, but the optimal management of older patients with brain tumors remains a matter of debate, since aggressive radiation treatments in this population may be associated with high risks of neurological toxicity and deterioration of quality of life. For such patients, a careful clinical status assessment is mandatory both for clinical decision making and for designing randomized trials to adequately evaluate the optimal combination of radiotherapy and chemotherapy.

Several randomized studies have demonstrated the efficacy and safety of chemotherapy for patients with glioblastoma or lymphoma; however, the use of radiotherapy given in association with chemotherapy or as salvage therapy remains an effective treatment option associated with survival benefit. Stereotactic techniques are increasingly used for the treatment of patients with brain metastases and benign tumors, including pituitary adenomas, meningiomas and acoustic neuromas. Although no randomized trials have proven the superiority of SRS over other radiation techniques in older patients with brain metastases or benign brain tumors, data extracted from recent randomized studies and large retrospective series suggest that SRS is an effective approach in such patients associated with survival advantages and toxicity profile similar to those observed in young adults. Future trials need to investigate the optimal radiation techniques and dose/fractionation schedules in older patients with brain tumors with regard to clinical outcomes, neurocognitive function, and quality of life.

Radionuclide I-131 Labeled Albumin-Paclitaxel Nanoparticles for Synergistic Combined Chemo-radioisotope Therapy of Cancer

Development of biocompatible/biodegradable materials with multiple functionalities via simple methods for cancer combination therapy has attracted great attention in recent years. Herein, paclitaxel (PTX), a popular anti-tumor chemotherapeutic drug, is used to induce the self-assembly of human serum albumin (HSA) pre-labeled with radionuclide I-131, obtaining 131I-HSA-PTX nanoparticles for combined chemotherapy and radioisotope therapy (RIT) of cancer. Such 131I-HSA-PTX nanoparticles show prolonged blood circulation time, high tumor specific uptake and excellent intra-tumor penetration ability. Interestingly, as revealed by in vivo photoacoustic imaging and ex vivo immunofluorescence staining, PTX delivered into the tumor by HSA-nanoparticle transportation can remarkably enhance the tumor local oxygen level and suppress the expression of HIF-1α, leading to greatly relieved tumor hypoxia. As the results, the combined in vivo chemotherapy & RIT with 131I-HSA-PTX nanoparticles in the animal tumor model offers excellent synergistic therapeutic efficacy, likely owing to the greatly modulated tumor microenvironment associated with PTX-based chemotherapy. Therefore, in this work, a simple yet effective therapeutic agent is developed for synergistic chemo-RIT of cancer, promising for future clinic translations in cancer treatment.

Phase I and II Study of Induction Chemotherapy With Methotrexate, Rituximab, and Temozolomide, Followed By Whole-Brain Radiotherapy and Postirradiation Temozolomide for Primary CNS Lymphoma: NRG Oncology RTOG 0227

PURPOSE

This study investigated the treatment of primary CNS lymphoma with methotrexate, temozolomide (TMZ), and rituximab, followed by hyperfractionated whole-brain radiotherapy (hWBRT) and subsequent TMZ. The primary phase I end point was the maximum tolerated dose of TMZ. The primary phase II end point was the 2-year overall survival (OS) rate. Secondary end points were preirradiation response rates, progression-free survival (PFS), neurologic toxicities, and quality of life.

PATIENTS AND METHODS

The phase I study increased TMZ doses from 100 to 150 to 200 mg/m(2). Patients were treated with rituximab 375 mg/m(2) 3 days before cycle 1; methotrexate 3.5 g/m(2) with leucovorin on weeks 1, 3, 5, 7, and 9; TMZ daily for 5 days on weeks 4 and 8; hWBRT 1.2 Gy twice-daily on weeks 11 to 13 (36 Gy); and TMZ 200 mg/m(2) daily for 5 days every 28 days on weeks 14 to 50.

RESULTS

Thirteen patients (one ineligible) were enrolled in phase I of the study. The maximum tolerated dose of TMZ was 100 mg/m(2). Dose-limiting toxicities were hepatic and renal. In phase II, 53 patients were treated. Median follow-up for living eligible patients was 3.6 years, and 2-year OS and PFS were 80.8% and 63.6%, respectively. Compared with historical controls from RTOG-9310, 2-year OS and PFS were significantly improved (P = .006 and .030, respectively). In phase II, the objective response rate was 85.7%. Among patients, 66% (35 of 53) had grade 3 and 4 toxicities before hWBRT, and 45% (24 of 53) of patients experienced grade 3 and 4 toxicities attributable to post-hWBRT chemotherapy. Cognitive function and quality of life improved or stabilized after hWBRT.

CONCLUSION

This regimen is safe, with the best 2-year OS and PFS achieved in any Radiation Therapy Oncology Group primary CNS lymphoma trial. Randomized trials that incorporate this regimen are needed to determine its efficacy compared with other strategies.

The influence of rituximab, high-dose therapy followed by autologous stem cell transplantation, and age in patients with primary CNS lymphoma

For patients with diffuse large B cell lymphoma without the involvement of the CNS, the addition of rituximab to standard chemotherapy has significantly improved survival. In this single-center, retrospective analysis, a total of 81 primary CNS lymphoma (PCNSL) patients treated in our institution between 2000 and 2011 were included. Beside first-line chemotherapy with or without rituximab, we evaluated the impact of age (≤/>60 years), autologous stem cell transplantation (ASCT +/-), and other factors upon overall survival (OS) and progression-free survival (PFS). In patients treated with rituximab (n = 27), 3-year OS was 77.8 % (95 % confidence interval (CI) 62-93 %). In contrast, in patients treated without rituximab (n = 52), 3-year OS was only 39.9 % (CI 27-53 %, Fig. 1). The difference in OS was significant in the univariate (p = 0.002) as well as in the multivariate analysis (p = 0.049, hazard ratio (HR) = 0.248). Patients ≤60 years of age (n = 28) had a 3-year OS of 78.2 % (CI 63-94 %); in patients >60 years (n = 51), 3-year OS was 38.7 % (CI 25-52 %). Patients who received high-dose therapy and ASCT had a 3-year OS of 85.2 % (CI 72-99 %), and 65.1 % were alive up to the time of analysis (range 9-131 months). Without ASCT, median OS was only 16 months (CI 11-21) and 3-year OS was 35.2 % (CI 22-48 %). Age and ASCT were significantly associated with better OS in univariate (p = 0.002 and p < 0.001) as well in multivariate analysis (p = 0.004, HR = 0.023 and p = 0.001, HR = 0.014). Rituximab treatment, ASCT, and age are independent prognostic factors for OS in the first-line treatment of PCNSL.

The role of radiation therapy in the management of primary central nervous system lymphoma

Primary central nervous system lymphoma (PCNSL) is an aggressive neoplasm with a poor prognosis. Early studies of whole brain radiation therapy (WBRT) alone revealed a robust initial response but high rates of local recurrence with long-term follow-up. The addition of high-dose methotrexate (HDMTX)-based chemotherapy improved the durability of disease control. However, delayed neurotoxicity emerged as an important complication, mainly in elderly patients. Therefore, researchers have investigated eliminating WBRT or reducing its dose. Multiple studies of chemotherapy alone have demonstrated inferior disease control. On the other hand, a phase III trial reported that WBRT may be deferred until relapse without compromising survival; however, this trial is fraught with flaws. A recent study of immunochemotherapy and dose-reduced WBRT demonstrated excellent outcomes. Currently, this regimen is being studied in a multi-institutional trial by the Radiation Therapy Oncology Group. WBRT maintains an important position in the armamentarium against PCNSL. This article aims to describe its evolving role.

The role of additional radiotherapy for primary central nervous system lymphoma

BACKGROUND

Prior to the introduction of the chemotherapeutic agent methotrexate, radiotherapy was the sole, first-line option for the treatment of individuals with primary central nervous system lymphoma (PCNSL), Now that methotrexate is available, the role of radiotherapy in the treatment of PCNSL has been called into question. Although various studies suggest promising results with regard to overall and progression-free survival with the use of chemotherapeutic regimens alone as well as in combination with radiotherapy, no evidence-based standard regimen has yet been defined.

OBJECTIVES

The objective of this review was to assess and summarise the evidence available regarding the efficacy and tolerability of radiotherapy in addition to chemotherapy in the treatment of immunocompetent individuals with PCNSL.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (issue 01.2014), MEDLINE from January 1950 to February 2014 and conference proceedings from 2005 to 2013. 

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing chemotherapy plus radiotherapy with chemotherapy alone in individuals with PCNSL. Outcomes defined in this review were overall survival, progression-free survival, response to treatment, adverse events, treatment related mortality and quality of life. We excluded trials in which the chemotherapy regimen differed between treatment arms, trials in which fewer than 80% of participants had PCNSL or those recruiting immunocompromised individuals with PCNSL.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the results of the search strategies for eligibility for this review. Both assessed risk of bias. Where relevant data was unavailable, we contacted the investigator by email.

MAIN RESULTS

Of the 556 potentially relevant studies only two met the inclusion criteria. One of those was excluded as the trial was abandoned prematurely and reported only preliminary results. The only analysed trial enrolled 551 participants receiving first-line chemotherapy (methotrexate) followed by whole brain radiotherapy (WBR) or receiving chemotherapy only (methotrexate followed by cytarabine in case of incomplete response). In this non-inferiority trial, the intention-to-treat (ITT) population consisted of 411 participants and the per-protocol (PP) population of 318 participants. We judged the potential for risk of bias in this open-label study as moderate.The estimated effect of chemotherapy plus WBR on survival was similar to that with chemotherapy alone but due to a wide CI we could not rule out the superiority of either therapy. This applied to both the ITT population (HR 1.01, 95% CI 0.79 to 1.30; P = 0.94) and the PP population (HR 1.06, 95% CI 0.80 to 1.40; P = 0.71) (moderate-quality evidence). Due to the low number of participants and a risk of detection bias we found low-quality evidence for an improvement in progression-free survival in participants in the ITT population receiving WBR in addition to chemotherapy (HR 0.79, 95% CI 0.63 to 0.99; P = 0.041). An improvement in PFS was also observed with WBR plus chemotherapy in participants in the PP population, but the CI was slightly wider and the result not significant (HR 0.82,95% CI 0.64 to 1.07; P = 0.14). Treatment-related mortality and health-related quality of life were not evaluated. Treatment-related neurotoxicity was assessed clinically in 79 participants, revealing signs of neurotoxicity in 49% of those receiving chemotherapy plus radiotherapy and in 26% of those receiving chemotherapy only (RR 1.85, 95% CI 0.98 to 3.48; P = 0.054) (very-low-quality evidence).

AUTHORS' CONCLUSIONS

In summary, the currently available evidence (one RCT) is not sufficient to conclude that WBR plus chemotherapy and chemotherapy alone have similar effects on overall survival in people with PCNSL. The findings suggest that the addition of radiotherapy (WBR) to chemotherapy may increase progression-free survival, but may also increase the incidence of neurotoxicity compared to chemotherapy only (methotrexate monotherapy). As the role of chemoradiotherapy in the treatment of PCNSL remains unclear, further prospective, randomised trials are needed before definitive conclusions can be drawn.

Intravitreal injection of methotrexate in an experimental rabbit model: determination of ultrastructural changes

PURPOSE

To investigate the ultrastructural changes of the rabbit retina induced by intravitreal methotrexate injection.

MATERIALS AND METHODS

Ten New Zealand white rabbits were enucleated bilaterally at different time periods after intravitreal methotrexate injection. One rabbit was used as control group and one rabbit was used as intact group. Histopathological examinations were performed under light and electron microscopy. Early (within first three days after injection) and long-term (one month after serial injections) effects of intravitreal methotrexate on the retina were investigated.

RESULTS

Retinal edema, vacuolization, and disintegration of mitochondria of the retinal cells were observed as early changes. The main long-term effects after serial injections were edema in the photoreceptor, inner nuclear, and ganglionic cell layers. Cellular disorganisation was seen on light microscopy. Electron microscopic examination revealed mitochondrial degeneration and vacuole formation in retinal cells, nuclear degeneration in outer nuclear layer, and membranous whorl formation in photoreceptor and nerve fiber layers.

CONCLUSIONS

High dose intravitreal methotrexate injection may cause significant ultrastructural changes in the rabbit retina in varying severity. This finding may highlight the potential side effects of methotrexate on human retina in higher doses.

The expression of hepatoma-derived growth factor in primary central nervous system lymphoma and its correlation with angiogenesis, proliferation and clinical outcome

Hepatoma-derived growth factor (HDGF), a potential predictive and prognostic marker in several human cancers, is the firstly reported member of the HDGF family of proteins containing a well-conserved N-terminal amino acid sequence. HDGF is implicated in tumorigenesis by direct angiogenic activity, and its expression is correlated with aggressive biological ability of cancer cells including proliferation and angiogenesis. So, we propose that HDGF may be a valuable factor in progression and prognosis for primary central nervous system lymphoma (PCNSL) through its angiogenic and proliferative activity. So, HDGF, CD31 and Ki67 expression in the specimens of 60 patients suffering from PCNSL was investigated by immunohistochemistry in this study. Their correlations with clinicopathologic features and prognosis were evaluated to determine whether HDGF, CD31 and Ki67 expression levels correlate with the prognosis of the 60 patients suffering from PCNSL. We found that all PCNSL specimens showed HDGF, CD31 and Ki67 expression with different expression levels. Statistical analysis showed that HDGF had a positive correlation with CD31, but not with Ki67. Patients with higher HDGF and CD31 expression level had poorer overall survival rates than those with lower expression levels of HDGF and CD31, while Ki67 expression level did not correlate with overall survival. Multivariate analysis revealed that postoperative adjuvant chemotherapy and high expression of HDGF was independent prognostic indicator of patient survival.

Primary CNS lymphoma: a clinician's guide

Primary CNS lymphoma is a high malignant disease of the brain which can lead rapidly to death if diagnosis and/or the start of treatment is delayed. The age at time of diagnosis is a strong factor influencing prognosis so that in younger patients <65 years of age long-term survival may be achieved in a substantial percentage of patients, while in elderly patients long-term survival is seen much more rarely. First-line therapy consists of high-dose methotrexate-based (poly)chemotherapy. This review provides an overview of clinical presentation, steps to diagnosis, detailed information about current treatment concepts and specific information for particular clinical situations.

Pathogenesis and management of primary CNS lymphoma

Primary CNS lymphoma (PCNSL), a rare variant of extranodal non-Hodgkin's lymphoma, may cause various neurological symptoms and signs. The best therapeutic strategy is still a matter of debate. High-dose methotrexate (HD-MTX) is the most active compound and should be used as the backbone for any chemotherapy applied. Several other chemotherapeutic drugs have been assessed in combination with HD-MTX, but no standard has yet been defined. Whole-brain radiotherapy is active against PCNSL, but typically does not confer long-lasting remission and is associated with significant neurotoxicity in many patients. The recently published G-PCNSL-SG1 trial has shown that consolidating whole-brain radiotherapy after HD-MTX-based chemotherapy does not prolong overall survival and may therefore be deferred. Combined systemic and intraventricular polychemotherapy, or high-dose chemotherapy followed by stem cell transplantation may offer cures to younger patients. Improving treatment regimens without adding significant (neuro-)toxicity should be the focus of ongoing and future studies.

Primary central nervous system lymphoma

INTRODUCTION

Primary central nervous system lymphoma is a rare subtype of extranodal non-Hodgkin lymphoma that accounts for 4% of central nervous system tumours.

PATIENTS AND METHODS

Retrospective review of 24 patients diagnosed with primary central nervous system lymphoma between 1990 and 2010. All patients were diagnosed using magnetic resonance imaging and the diagnosis was confirmed surgically.

RESULTS

Of the 24 patients analysed, all except 4 were immunocompetent. Median age at diagnosis was 59.3 years (range 13-79) and the sex ratio (male to female) was 1:1.1. Cognitive decline (in 33.4%) and headache (in 25%) were the most common complaints. Diagnosis was performed In 13 cases (54%) following craniotomy and in the other 11 cases (46%) after stereotactic biopsy. Breakdown by pathology was as follows: 22 cases of B-cell lymphoma (91.6%), 1 case of anaplastic large-cell lymphoma, and 1 case of T-cell lymphoma. Mean survival time was 12.8 months with an overall 1-year survival rate of 37.5%.

CONCLUSIONS

Primary central nervous system lymphoma often presents in the sixth decade with cognitive decline, headache, and focal neurological deficits. A single intracranial lesion was present in 75% of the patients (18 cases), and the remaining 25% (6 cases) had between 2 and 4 lesions. Preoperative clinical status was the most important factor determining prognosis.

Primary central nervous system lymphoma: implication of high-dose chemotherapy followed by auto-SCT

Primary central nervous system lymphoma is a rare and distinct subtype of non-Hodgkin's lymphoma that is sensitive to radiation and chemotherapy. Decisions regarding the initial therapeutic approach are influenced by age and risk of therapy-related neurotoxicity. Despite several albeit small phase II studies, and the acknowledged need for larger prospective trials, there is supporting evidence to consider auto-SCT following induction chemotherapy in patients with good performance status. The international extranodal lymphoma study group is conducting a randomized phase II study comparing consolidative radiation therapy to high-dose therapy. Novel therapeutic options including early aggressive approach with upfront auto-SCT and strategies to prevent relapse following transplantation is an area of focus.

How I treat primary CNS lymphoma

Primary CNS lymphoma (PCNSL) is a rare malignancy with peculiar clinical and biologic features, aggressive course, and unsatisfactory outcome. It represents a challenge for multidisciplinary clinicians and scientists as therapeutic progress is inhibited by several issues. Molecular and biologic knowledge is incomplete, limiting the identification of new therapeutic targets, and the particular microenvironment of this malignancy, and sanctuary sites where tumor cells grow undisturbed, strongly affects treatment efficacy. Moreover, active treatments are known to be associated with disabling neurotoxicity, posing the dilemma of whether to intensify therapy to improve the cure rate or to de-escalate treatment to avoid sequels. The execution of prospective trials is also difficult because of the rarity of the tumor and the impaired general condition and poor performance status of patients. Thus, level of evidence is low, with consequent uncertainties in therapeutic decisions and lack of consensus on primary endpoints for future trials. Despite this unfavorable background, laboratory and clinical researchers are coordinating efforts to develop new ideas, resulting in the recent publication of studies on PCNSL's biology and molecular mechanisms and of the first international randomized trials. Herein, these important contributions are analyzed to provide recommendations for everyday practice and the rationale for future trials.

Factors influencing the response to high dose methotrexate-based vincristine and procarbazine combination chemotherapy for primary central nervous system lymphoma

The authors investigated objective response rate to high dose methotrexate (HDMTX)-based combination chemotherapy in primary central nervous system lymphoma (PCNSL), and sought to identify factors that influence response to HDMTX-based combination therapy. Prospective observational analysis was performed on 52 PCNSL patients. All patients received HDMTX (3.5 g/m(2)) and vincristine (1.4 mg/m(2)/day) for one day during weeks 1, 3, 5, 7, and 9, and procarbazine (100 mg/m(2)/day) for one week during weeks 1, 5, and 9. Forty-one patients (78.8%) achieved complete or partial remission. Higher objective response rates were observed for patients with: 1) age < 60 yr; 2) Eastern Cooperative Oncology Group (ECOG) performance score of < 2; 3) low risk status as defined by the International Extranodal Lymphoma Study Group; 4) p53 positivity; 5) XBP-1 negativity; 6) MUM-1 negativity; and 7) homogenous gadolinium enhancement in MR images. Multivariate analysis showed that ECOG performance score of < 2, low risk, negativity for XBP-1, homogenous gadolinium enhancement by MRI, and response to chemotherapy were associated with longer overall survival. In particular, it is interesting to note that patients with a PCNSL that is homogeneously enhanced by gadolinium have a higher objective response rate, and a longer progression-free survival and overall survival.

Neurologic complications after intrathecal liposomal cytarabine in combination with systemic polychemotherapy in primary CNS lymphoma

Intrathecal application of liposomal cytarabine (Ara-C) (DepoCyte(®)) has been associated with neurotoxicity when applied as part of a polychemotherapy regimen. Patients with primary central nervous system lymphoma treated with high-dose systemic methotrexate (MTX)- and Ara-C-based polychemotherapy including six cycles of liposomal Ara-C (50 mg intrathecally every 3 weeks) were prospectively monitored for neurotoxic side-effects. Between November 2005 and February 2009, 149 intrathecal applications of liposomal cytarabine (DepoCyte(®)) were carried out in 33 patients, 7 (21%) of whom developed an incomplete conus medullaris/cauda equina syndrome with incontinence for bladder (6) and bowel function (3) or lumbosacral polyradicular paresis (1), resolving only incompletely over a follow-up period of 9-30 months. In six of these seven patients, lumbosacral magnetic resonance imaging (MRI) was negative for leptomeningeal infiltration or arachnoiditis. Cerebrospinal fluid (CSF) analysis performed in six of these seven patients showed normal cell count in all and increased total protein in four of them. One patient among these seven suffered a seizure without other identifiable causes. Conus/cauda syndrome has to be considered as a serious potential neurotoxic side-effect in patients receiving liposomal Ara-C as part of a multimodal regimen including high-dose systemic MTX and Ara-C.

Primary central nervous system lymphoma

There is no class I evidence for any therapeutic option in primary central nervous system lymphoma (PCNSL). When possible, patients should be included in clinical trials. The role of surgery is restricted to stereotactic biopsy in order to gain material for histopathologic diagnosis. Radiotherapy alone is associated with a median survival of no more than 1.5 years; cure is exceptional. However, in patients aged younger than 60 years, cure is the therapeutic aim. Polychemotherapy based on high-dose methotrexate with deferred radiation results in long-term survival in most of these patients and possibly cure in a substantial fraction of these patients. With regard to chemotherapy in PCNSL, the following must be considered: 1) the most efficient drug in PCNSL is methotrexate at a dosage of at least 1.5 g/m(2) per single dose; 2) methotrexate alone will lead to complete remission in only some patients, whereas the combination of methotrexate with other drugs is more efficient; and 3) the value of additional intraventricular chemotherapy and the necessity of "consolidation" radiotherapy after response to chemotherapy are not yet defined. For patients aged older than 60 years, no curative regimen with acceptable toxicity has yet been established. The combination of radiotherapy with methotrexate-based chemotherapy leads to severe long-term neurotoxic sequelae, ie, cognitive dysfunction, in most older patients and in some patients aged younger than 60 years.

Current therapeutic approaches to primary CNS lymphoma

The best therapeutic management in primary CNS lymphomas remains to be defined due to the small size and short follow-up of retrospective series, methodological pitfalls and limited number of prospective studies, and the paucity of randomized trials. This review focuses on the current therapeutic approaches, most commonly used drugs, role of intrathecal chemotherapy and indications for consolidation radiotherapy, providing recommendations for ordinary clinical practice. Some important therapeutic issues, such as the management of meningeal and intraocular lymphomas, as well as the relevance of salvage therapy as a playground for evaluation of new drugs, are also analyzed. Finally, the main open questions, as well as current and expected investigation trends are discussed.

Management of immunocompetent patients with primary central nervous system lymphoma

Primary central nervous system (CNS) lymphoma (PCNSL) is a non-Hodgkin lymphoma that arises within and is confined to the CNS. Recent data have suggested an increasing incidence in immunocompetent individuals, with a peak of incidence between 60 and 70 years of age. Patients with PCNSL present mostly with symptoms of increased intracranial pressure. The clinical management of these patients remains controversial, and the optimal treatment for patients with PCNSL has not yet been defined. Surgery, even if macroscopically radical, does not improve survival because of the multifocal and infiltrative nature of PCNSL; furthermore, the deep location of most of these tumors makes patients susceptible to serious and irreversible neurologic sequelae. Corticosteroids have a specific role in the treatment of patients with PCNSL, whose disease is sensitive to them as a chemotherapeutic agent. PCNSL is an extremely radiation-sensitive neoplasm; whole-brain radiation therapy plus corticosteroids was the first modality of treatment for patients with this neoplasm until 10 years ago, with a low cure rate and a high local recurrence rate. PCNSL is also a chemosensitive neoplasm; while the optimal choice, sequence, and combination of appropriate agents for efficacious treatment of patients with PCNSL has yet to be determined. An essential component of therapy must include an adequate drug delivery behind a normal blood-brain barrier. Methotrexate is the agent with the most proven activity in PCNSL. Combined-modality therapy has improved survival, but relapse is still common, and late neurologic toxicity is a significant complication, especially in older patients, who represent the majority of immunocompetent patients with PCNSL.

Primary central nervous system lymphoma in Japan: changes in clinical features, treatment, and prognosis during 1985-2004

We have conducted nationwide surveys of primary central nervous system lymphoma (PCNSL) treated since 1985. In the present study, we newly collected data between 2000 and 2004 and investigated changes in clinical features and outcome over time. A total of 739 patients with histologically proven PCNSL under going radiotherapy were analyzed. Seventeen institutions were surveyed, and data on 131 patients were collected. These data were compared with updated data that were previously obtained for 466 patients treated during 1985-1994 and 142 patients treated during 1995-1999. Recent trends toward decrease in male/female ratio, increase in aged patients, and increase in patients with multiple lesions were seen. Regarding treatment, decrease in attempts at surgical tumor removal and increases in use of systemic chemotherapy and methotrexate (MTX)-containing regimens were observed. The median survival time was 18, 29, and 24 months for patients seen during 1985-1994, 1995-1999, and 2000-2004, respectively, and the respective 5-year survival rates were 15%, 30%, and 30%. In groups seen during 1995-1999 and during 2000-2004, patients who received systemic or MTX-containing chemotherapy had better prognosis than those who did not. Multivariate analysis of all patients seen during 1985-2004 suggested the usefulness of MTX-containing chemotherapy as well as the importance of age, lactate dehydrogenase level, and tumor multiplicity as prognostic factors. Thus, this study revealed several notable changes in clinical features of PCNSL patients. The prognosis improved during the last 10 years. Advantage of radiation plus chemotherapy, especially MTX-containing chemotherapy, over radiation alone was suggested.

Increasing incidence and continued dismal outcome of primary central nervous system lymphoma in Norway 1989-2003 : time trends in a 15-year national survey

BACKGROUND

The incidence of primary central nervous system lymphoma (PCNSL) appears to be increasing in some countries, whereas it is stable in others. Many reports the last decades have suggested that there have been improvements in the treatment of PCNSL. The objective of this study was to analyze time trends in the incidence, clinical features, histologic diagnosis, treatment, and outcome of nonacquired immunodeficiency syndrome (non-AIDS) PCNSL in Norway from 1989 to 2003.

METHODS

Patients were identified by a chart review of all patients who had a recorded diagnosis of PCNSL from 1989 to 2003 in The Norwegian Cancer Registry. The histologic and cytologic material from each patient was re-examined by pathologists. Time trends were analyzed according to year of diagnosis grouped into 3 5-year periods: 1989-1993, 1994-1998, and 1999-2003.

RESULTS

There were 98 patients who had confirmed, newly diagnosed non-AIDS PCNSL in Norway from 1989 to 2003. The incidence rate increased during the consecutive 5-year periods from 0.89 per million during 1989 to 1993, to 1.74 per million during 1994 to 1998, and to 1.82 per million during 1999 to 2003 (P = .013). Diagnostic delay and overall survival did not improve with time. Survival decreased from 1999 to 2003 compared with survival from 1994 to 1998, which was explained in part by reduced performance status and fewer patients receiving combined chemotherapy and radiotherapy during 1999 to 2003. In multivariate analysis, age </=50 years, a good performance status, and active treatment (especially combined chemotherapy and radiotherapy) significantly improved survival.

CONCLUSIONS

The incidence of PCNSL is increasing in Norway. Despite diagnostic and therapeutic advances over the last decades, neither a reduction in diagnostic delay nor any improvement in overall survival with time was observed. The search for improved understanding of etiology and treatment should be intensified.

Primary central nervous system lymphoma in children

Primary central nervous system lymphoma (PCNSL) is a very rare brain tumor in children, and the optimal management and prognosis of such patients have yet to be defined. In this study, the incidence rate, clinical features, diagnosis, and treatment of childhood PCNSL are reviewed. Except for human immunodeficiency virus-related PCNSL, the prognosis for patients with this tumor type is significantly better in children than in adults. In the absence of prospective studies, it is very difficult to determine the true incidence and the best therapeutic strategy for this rare entity. The majority of children with PCNSL, however, can achieve long-term remissions with intensive chemotherapy alone (an estimated 70% 5-year event-free survival rate), and cranial irradiation can be reserved for relapse of the disease. Further progress in the management of childhood PCNSL will require prospective multinational studies.

High-dose chemotherapy with autologous stem-cell transplantation and hyperfractionated radiotherapy as first-line treatment of primary CNS lymphoma

PURPOSE

To improve survival and reduce toxicity in primary CNS lymphoma (PCNSL) treatment, we conducted a multicenter phase II study with early high-dose chemotherapy (HDT) and autologous stem-cell transplantation (ASCT) followed by hyperfractionated whole-brain radiotherapy (WBRT) for newly diagnosed PCNSL patients younger than 65 years of age.

PATIENTS AND METHODS

Chemotherapy included three steps: three cycles of methotrexate (8 g/m2); cytarabine (AraC; two doses of 3 g/m2) and thiotepa (40 mg/m2) followed by stem-cell harvest; HDT with carmustine (400 mg/m2) and thiotepa (two doses of 5 mg/kg body weight) followed by ASCT. WBRT (45 Gy, two doses of 1 Gy/d) was administered for consolidation.

RESULTS

Thirty patients with PCNSL younger than 65 years of age (median, 54 years; range, 27 years to 64 years) were enrolled (nine pilot-phase; 21 phase II). Twenty-eight patients responded to methotrexate: six patients with complete remission (CR), 15 patients with partial remission (PR), and seven patients with stable disease (SD) with clinical improvement. Of 26 patients proceeding to AraC and thiotepa, 10 patients achieved CR, 14 patients achieved PR, one patient experienced SD with clinical improvement, and one patient suffered disease progression. Twenty-three patients received HDT plus ASCT, resulting in 15 patients with CRs and eight patients with PRs. After WBRT, 21 of 21 patients had CRs. One patient died from liver failure after methotrexate. HDT was well tolerated apart from WHO grade 3/4 cytopenia. With a median follow-up of 63 months (range, 4 months to 84 months), 5-year overall survival probability is 69% for all patients and 87% for the 23 patients receiving HDT plus ASCT. The 5-year probability of relapse-related death is 21% for all patients (n = 30) and 8.7% for patients treated with HDT plus ASCT (n = 23).

CONCLUSION

Sequential systemic methotrexate and AraC and thiotepa followed by HDT plus ASCT and hyperfractionated WBRT is very effective with little toxicity as initial therapy for PCNSL.

International study on low-grade primary central nervous system lymphoma

OBJECTIVE

The aim of this study was to characterize the clinical presentation, course, and outcome of low-grade primary central nervous system lymphoma.

METHODS

Cases were assessed in a retrospective series collected from 18 cancer centers in 5 countries.

RESULTS

Forty patients (18 men, 22 women; median age, 60 years [range, 19-78]) were identified. Involvement of a cerebral hemisphere or deeper brain structures was seen in 37 patients, only leptomeningeal involvement in 2 patients, and spinal cord disease in 1 patient. Chemotherapy/radiotherapy was conducted in 15 patients, radiotherapy alone in 12, chemotherapy alone in 10, and tumor resection alone in 2, whereas 1 patient received no treatment. The median progression-free, disease-specific, and overall survival were 61.5 (range, 0-204), 130 (range, 1-204), and 79 (range, 1-204) months, respectively. Only age 60 years or older was associated with shorter progression-free (p = 0.009), disease-specific (p = 0.015), and overall survival (p = 0.001) in multivariate analysis.

INTERPRETATION

Low-grade primary central nervous system lymphoma differs from the high-grade subtype in its pathological, clinical, and radiological features. It has a better long-term outcome than primary central nervous system lymphoma in general with age 60 years or older adversely affecting survival.

Primary central nervous system lymphoma of the brain stem responding favorably to radiosurgery: a case report and literature review

OBJECTIVE

To explore various therapeutic alternatives and evaluate the clinical results of patients with primary central nervous system lymphoma (PCNSL). We report a case of PCNSL with involvement of the brain stem managed with radiosurgery using the Leksell gamma knife as the treatment modality.

CASE DESCRIPTION

A 55-year-old white woman presented with complaints of weakness on the left side of her body and double vision associated with a frontal headache. Nervous system examination revealed right-sided oculomotor palsy and left-sided motor paresis, grade 2/5, in both upper and lower limbs. Her Karnofsky performance score was 50. A contrast-enhanced magnetic resonance imaging scan of the brain revealed an irregular space-occupying lesion in the pons that enhanced uniformly with gadolinium. A frame-based stereotactic biopsy was performed revealing a B-cell malignant lymphoma. Subsequently, stereotactic radiosurgery using the Leksell gamma knife was performed. A dose of 11 Gy was delivered to the tumor margin. A follow-up magnetic resonance imaging scan after 2 months revealed a 50% reduction in the size of the enhancing lesion.

CONCLUSION

Our own results and limited evidence from the literature suggest stereotactic radiosurgery as a potentially safe and effective treatment option in patients with PCNSL.

First-line autologous stem cell transplantation in primary CNS lymphoma

The treatment of primary central nervous system lymphoma (PCNSL) has been considerably improved over recent years. In this article, we report six cases of PCNSL treated by first-line induction chemotherapy followed by intensive chemotherapy and autologous stem cell transplantation (ASCT). Six immunocompetent patients presenting with a PCNSL, confirmed by thoraco-abdomino-pelvic computer tomography scan and bone marrow biopsy, were treated with induction chemotherapy followed by BEAM intensive chemotherapy and ASCT and radiotherapy. At the end of the treatment, all the patients were in complete remission. After a median follow-up of 41.5 months (17-70 months), four patients were alive without signs of relapse (median survival: 35.5 months). Two patients died from relapse at 19 and 23 months. The neurotoxicity was low with epilepsy in one patient and persistent left side dysesthesia in another one. These results are fairly encouraging. Other studies with greater numbers of patients and longer follow-up are needed to confirm this study.

FDG-PET in immunocompetent patients with primary central nervous system lymphoma: correlation with MRI and clinical follow-up

PURPOSE

The role of FDG-PET in primary central nervous system lymphoma (PCNSL) is unclear. It was the aim of this study to investigate the role of FDG-PET in detecting PCNSL and in predicting response to chemotherapy.

METHODS

An FDG-PET scan of the brain was performed in 15 patients with histologically proven PCNSL (16 PET examinations, Siemens ECAT EXACT). PET was planned to investigate patients at the time of primary diagnosis, after chemotherapy and at the time of suspected relapse in seven, five and three cases, respectively. All except two patients simultaneously underwent MRI of the brain. FDG-PET results were correlated with histological results after stereotactic biopsy (primary diagnosis group) and with clinical data and MRI during follow-up.

RESULTS

Six of the seven patients in the primary diagnosis group demonstrated a true positive finding (86%). In one of the true positive PET patients, there were two tumour lesions, one of which was only detectable on the FLAIR MRI sequence. In five patients, FDG-PET showed no sign of PCNSL during ongoing chemotherapy. These results were confirmed by the clinical follow-up (mean 26.6 months). MRI demonstrated minimal residual disease which had disappeared on further follow-up MRI in three of these five patients at the time of PET scanning. Recurrence of disease was confirmed concordantly by FDG-PET and MRI in three different patients. The standardised uptake value of all tumours was 10.2 (4.3-13.7).

CONCLUSION

PCNSLs demonstrate high FDG uptake and can be diagnosed by FDG-PET with high sensitivity. It seems that FDG-PET is suitable for early therapeutic monitoring after chemotherapy.