Ten-year survival of children with acute lymphoblastic leukemia: a report from the Children's Oncology Group

A qualitative inquiry of communication based barriers to the diagnosis of pediatric cancer: Perceptions of primarily Spanish-speaking caregivers

BACKGROUND

Primarily Spanish-speaking cancer patients and caregivers often experience non-congruence with healthcare providers about beliefs, values, and knowledge of cancer. Our goal was to describe how communication related to the diagnosis of cancer was influenced by culture and language among primarily Spanish-speaking caregivers of pediatric cancer patients.

METHODS

Caregivers participated in three focus groups about their experiences with their child's diagnosis, communication issues, and understanding of their child's diagnosis and treatment plan. Focus groups were audio recorded, transcribed, and qualitatively analyzed using interpretive description.

RESULTS

Three themes emerged: 1) Negative experiences and barriers during the cancer diagnosis and treatment, 2) Miscommunication and system complexity, and 3) Language barriers throughout the diagnostic process. Due to barriers and negative experiences, some caregivers reported that their child's diagnosis was delayed, that providers sometimes used dehumanizing language, and that they were confused about diagnostic testing and treatment.

CONCLUSION

Cultural and linguistic disparities in pediatric oncology must be systematically addressed at the provider, clinic, and system level.

PRACTICE IMPLICATIONS

High-quality cancer care delivered by oncologists and cancer care teams should include cultural humility when discussing the cancer diagnosis and prognosis.

Prevalence and Risk Factors for Metabolic Syndrome Among Childhood Acute Lymphoblastic Leukemia Survivors: Experience From South India

BACKGROUND AND OBJECTIVES

Improved survival of childhood acute lymphoblastic leukemia (ALL) has diverted attention to the long-term consequences of the treatment; metabolic abnormalities being one of the most important issues.

METHODS

Children diagnosed with ALL at age 14 years and younger at Regional Cancer Centre in South India who completed treatment and who were on follow-up for >2 years were enrolled in the study between April 1, 2018 and March 31, 2019. They were prospectively evaluated for the presence of metabolic syndrome (MS) and associated risk factors.

RESULTS AND DISCUSSION

A total of 277 survivors of pediatric ALL were recruited during the study period. MS was present in 8.3% (n=23) and 6% (n=13) survivors by National Cholesterol Education Programme Adult Treatment Panel III (NCEPATP III) and International Diabetes Federation (IDF) criteria, respectively. The prevalence of overweight and obesity in the survivors was 9% and 13%. The prevalence of increased waist circumference, low high-density lipoprotein cholesterol, elevated triglycerides, elevated fasting glucose, and increased blood pressure were 10.5%, 28.9%, 24.9%, 2.5%, and 9%, respectively. Overweight/obese survivors were at an increased risk for developing MS (odds ratio=17.66; 95% confidence interval=6.2-50.16, P=0.001). Survivors who received cranial radiotherapy were at an elevated risk for having low high-density lipoprotein cholesterol (P=0.001).

CONCLUSIONS

In our study, the prevalence of MS was higher in childhood ALL survivors, as compared with the general population. The study points to the need for regular screening of pediatric ALL survivors for early detection of MS, along with lifestyle modification in those with metabolic abnormalities, to curb the growing incidence of coronary artery disease.

Long-Term Outcomes of Modified St Jude Children's Research Hospital Total Therapy XIIIB and XV Protocols for Thai Children With Acute Lymphoblastic Leukemia

BACKGROUND

We studied long-term outcomes and prognostic features of Thai children with acute lymphoblastic leukemia treated with modified St Jude Children's Research Hospital (SJCRH) protocols.

PATIENTS AND METHODS

Pediatric patients newly diagnosed with acute lymphoblastic leukemia were included. From 1997 to 2003, the first group received modified Total Therapy XIIIB (previous protocol). From 2004 to 2014, the latter had modified Total Therapy XV (current protocol).

RESULTS

In 250 patients, the event-free survival rates (± standard error) of the previous protocol (n = 95) were 82.8 ± 3.9%, 81.7 ± 4.0%, and 81.7 ± 4.0% at 5, 10, and 15 years, respectively; current protocol event-free survival rates (n = 155) were 84 ± 3.0%, 80.8 ± 3.4%, and 80.8 ± 3.4%, respectively. Previous protocol overall survival rates for the same years were 89.2 ± 3.2%, 84.8 ± 3.8%, and 84.8 ± 3.8%, and for the current protocol were 90 ± 2.5%, 86.9 ± 3.2%, and 83.7 ± 4.4%. Previous protocol relapses were 10.5% (10 patients), with 7 having isolated hematologic and 3 isolated/combined central nervous system relapses. Current protocol relapses were 9.7% (15 patients), with 7 having isolated hematologic, 6 isolated/combined central nervous system, and 2 extramedullary relapses. Patients with leukocyte counts over 100 × 10⁹/L and who had disease classified as high risk had worse event-free survival using the previous protocol. However, only initial leukocyte counts of ≥ 100 × 10⁹/L predicted adverse outcomes under the current protocol. Minimal residual disease positivity was a prognostic factor of worse overall survival only for previous protocol patients.

CONCLUSION

Favorable outcomes of childhood acute lymphoblastic leukemia occurred using adapted SJCRH protocols, perhaps because of multidisciplinary care teams and improved parent advocacy. Inferior outcomes might be prevented by addressing predictive factors to ameliorate monitoring and care.

B lymphoblastic leukemia/lymphoma: new insights into genetics, molecular aberrations, subclassification and targeted therapy

B lymphoblastic leukemia/lymphoma (B-ALL) is a clonal hematopoietic stem cell neoplasm derived from B-cell progenitors, which mostly occurs in children and adolescents and is regarded as one of top leading causes of death related to malignancies in this population. Despite the majority of patients with B-ALL have fairly good response to conventional chemotherapeutic interventions followed by hematopoietic stem cell transplant for the last decades, a subpopulation of patients show chemo-resistance and a high relapse rate. Adult B-ALL exhibits similar clinical course but worse prognosis in comparison to younger individuals. Ample evidences have shown that the clinical behavior, response rate and clinical outcome of B-ALL rely largely on its genetic and molecular profiles, such as the presence of BCR-ABL1 fusion gene which is an independent negative prognostic predictor. New B-ALL subtypes have been recognized with recurrent genetic abnormalities, including B-ALL with intrachromosomal amplification of chromosome 21 (iAMP21), B-ALL with translocations involving tyrosine kinases or cytokine receptors (“BCR-ABL1-like ALL”). Genome-wide genetic profiling studies on B-ALL have extended our understanding of genomic landscape of B-ALL, and genetic mutations involved in various key pathways have been illustrated. These include CRLF2 and PAX5 alterations, TP53, CREBBP and ERG mutations, characteristic genetic aberrations in BCR-ABL1-like B-ALL and others. The review further provides new insights into clinical implication of the genetic aberrations in regard to targeted therapy development.

Gene Expression Profiling of Acute Lymphoblastic Leukemia in Children with Very Early Relapse

BACKGROUND AND AIMS

Acute lymphoblastic leukemia (ALL) is the most common childhood cancer worldwide. Mexican patients have high mortality rates, low frequency of good prognosis biomarkers (i.e., ETV6-RUNX1) and a high proportion is classified at the time of diagnosis with a high risk to relapse according to clinical features. In addition, very early relapses are more frequently observed than in other populations. The aim of the study was to identify new potential biomarkers associated with very early relapse in Mexican ALL children through transcriptome analysis.

METHODS

Microarray gene expression profiling on bone marrow samples of 54 pediatric ALL patients, collected at time of diagnosis and/or at relapse, was performed. Eleven patients presented relapse within the first 18 months after diagnosis. Affymetrix Human Transcriptome Array 2.0 (HTA 2.0) was used to perform gene expression analysis. Annotation and functional enrichment analyses were carried out using Gene Ontology, KEGG pathway analysis and Ingenuity Pathway Analysis tools.

RESULTS

BLVRB, ZCCHC7, PAX5, EBF1, TMOD1 and BLNK were differentially expressed (fold-change >2.0 and p value <0.01) between relapsed and non-relapsed patients. Functional analysis of abnormally expressed genes revealed their important role in cellular processes related to the development of hematological diseases, cancer, cell death and survival and in cell-to-cell signaling interaction.

CONCLUSIONS

Our data support previous findings showing the relevance of PAX5, EBF1 and ZCCHC7 as potential biomarkers to identify a subgroup of ALL children in high risk to relapse.

Feasibility Study of a Novel Experimental Induction Protocol Combining B43-PAP (Anti-CD19) Immunotoxin With Standard Induction Chemotherapy in Children and Adolescents With Relapsed B-Lineage ALL: A Report From the Children's Oncology Group

BACKGROUND

B43-pokeweed antiviral protein (B43-PAP) is a high-affinity anti-CD19 immunotoxin that is capable of causing apoptotic death in B-lineage leukemic cells with a drug-resistant phenotype. B43-PAP exhibited in vivo antileukemic activity in preclinical studies as well as on a single-agent phase I clinical trial. This pediatric phase I/II study evaluated the toxicity profile and efficacy of B43-PAP immunotoxin in combination with standard induction chemotherapy in children and adolescents with relapsed CD19-positive B-lineage acute lymphoblastic leukemia (B-ALL). Pharmacokinetic profile and immunogenicity of B43-PAP were assessed.

EXPERIMENTAL DESIGN

B43-PAP in combination with standard 3 and 4-drug induction chemotherapy was administered on days 9-13 and 21-25 of a 28-day treatment course with vincristine, prednisone, L-asparaginase, daunomycin, and intrathecal methotrexate. Thirty patients with relapsed B-ALL were enrolled on study CCG-0957.

RESULTS

Grade III/IV nonhematologic dose-limiting toxicities were encountered in 4 patients evaluable for toxicity and included myalgias, motor dysfunction, pulmonary toxicity, and elevated liver transaminase. Dose-limiting toxicities occurred only with the 4-drug regimen. Fourteen patients achieved a complete remission at the end of induction among the 20 patients evaluable for response.

CONCLUSIONS

B43-PAP in combination with standard induction chemotherapy can be safely administered and exhibits clinical antileukemic activity against relapsed B-ALL.

CD19-antigen specific nanoscale liposomal formulation of a SYK P-site inhibitor causes apoptotic destruction of human B-precursor leukemia cells

We report the anti-leukemic potency of a unique biotargeted nanoscale liposomal nanoparticle (LNP) formulation of the spleen tyrosine kinase (SYK) P-site inhibitor C61. C61-loaded LNP were decorated with a murine CD19-specific monoclonal antibody directed against radiation-resistant CD19-receptor positive aggressive B-precursor acute lymphoblastic leukemia (ALL) cells. The biotargeted C61-LNP were more potent than untargeted C61-LNP and consistently caused apoptosis in B-precursor ALL cells. The CD19-directed C61-LNP also destroyed B-precursor ALL xenograft cells and their leukemia-initiating in vivo clonogenic fraction. This unique nanostructural therapeutic modality targeting the SYK-dependent anti-apoptotic blast cell survival machinery shows promise for overcoming the clinical radiochemotherapy resistance of B-precursor ALL cells.

Recombinant human CD19L-sTRAIL effectively targets B cell precursor acute lymphoblastic leukemia

Patients with B cell precursor acute lymphoblastic leukemia (BPL) respond well to chemotherapy at initial diagnosis; however, therapeutic options are limited for individuals with BPL who relapse. Almost all BPL cells express CD19, and we recently cloned the gene encoding a natural ligand of the human CD19 receptor (CD19L). We hypothesized that fusion of CD19L to the soluble extracellular domain of proapoptotic TNF-related apoptosis-inducing ligand (sTRAIL) would markedly enhance the potency of sTRAIL and specifically induce BPL cell apoptosis due to membrane anchoring of sTRAIL and simultaneous activation of the CD19 and TRAIL receptor (TRAIL-R) apoptosis signaling pathways. Here, we demonstrate that recombinant human CD19L-sTRAIL was substantially more potent than sTRAIL and induced apoptosis in primary leukemia cells taken directly from BPL patients. CD19L-sTRAIL effectively targeted and eliminated in vivo clonogenic BPL xenograft cells, even at femtomolar-picomolar concentrations. In mice, CD19L-sTRAIL exhibited a more favorable pharmacokinetic (PK) profile than sTRAIL and was nontoxic at doses ranging from 32 fmol/kg to 3.2 pmol/kg. CD19L-sTRAIL showed potent in vivo antileukemic activity in NOD/SCID mouse xenograft models of relapsed and chemotherapy-resistant BPL at nontoxic fmol/kg dose levels. Together, these results suggest that recombinant human CD19L-sTRAIL has clinical potential as a biotherapeutic agent against BPL.

Liver transplantation in an adolescent with acute liver failure from acute lymphoblastic leukemia

The most common identifiable causes of acute liver failure in pediatric patients are infection, drug toxicity, metabolic disease, and autoimmune processes. In many cases, the etiology of acute liver failure cannot be determined. Acute leukemia is an extremely rare cause of acute liver failure, and liver transplantation has traditionally been contraindicated in this setting. We report a case of acute liver failure in a previously healthy 15-yr-old male from pre-B-cell acute lymphoblastic leukemia. He underwent liver transplantation before the diagnosis was established, and has subsequently received chemotherapy for pre-B-cell acute lymphoblastic leukemia. He is currently alive 31 months post-transplantation. The published literature describing acute lymphoblastic leukemia as a cause of acute liver failure is reviewed.

Thymoquinone induces mitochondria-mediated apoptosis in acute lymphoblastic leukaemia in vitro

There has been a growing interest in naturally occurring compounds from traditional medicine with anti-cancer potential. Nigella sativa (black seed) is one of the most widely studied plants. This annual herb grows in countries bordering the Mediterranean Sea and India. Thymoquinone (TQ) is an active ingredient isolated from Nigella sativa. The anti-cancer effect of TQ, via the induction of apoptosis resulting from mitochondrial dysfunction, was assessed in an acute lymphocyte leukemic cell line (CEMss) with an IC₅₀ of 1.5 µg/mL. A significant increase in chromatin condensation in the cell nucleus was observed using fluorescence analysis. The apoptosis was then confirmed by Annexin V and an increased number of cellular DNA breaks in treated cells were observed as a DNA ladder. Treatment of CEMss cells with TQ encouraged apoptosis with cell death-transducing signals by a down-regulation of Bcl-2 and up-regulation of Bax. Moreover, the significant generation of cellular ROS, HSP70 and activation of caspases 3 and 8 were also observed in the treated cells. The mitochondrial apoptosis was clearly associated with the S phase cell cycle arrest. In conclusion, the results from the current study indicated that TQ could be a promising agent for the treatment of leukemia.

Scaling up cancer care for children without medical insurance in developing countries: The case of Mexico

BACKGROUND

In 2006, the Mexican government launched the Fund for Protection Against Catastrophic Expenditures (FPGC) to support financially healthcare of high cost illnesses. This study aimed at answering the question whether FPGC improved coverage for cancer care and to measure survival of FPGC affiliated children with cancer.

PROCEDURE

A retrospective cohort study (2006-2009) was conducted in 47 public hospitals. Information of children and adolescents with cancer was analyzed. The coverage was estimated in accordance with expected number of incident cases and those registered at FPGC. The survival was analyzed by using Kaplan-Meier survival curves and Cox proportional hazards regression modeling.

RESULTS

The study included 3,821 patients. From 2006 to 2009, coverage of new cancer cases increased from 3.3% to 55.3%. Principal diagnoses were acute lymphoblastic leukemia (ALL, 46.4%), central nervous system (CNS) tumors (8.2%), and acute myeloid leukemia (AML, 7.4%). The survival rates at 36 months were ALL (50%), AML (30.5%), Hodgkin lymphoma (74.5%), Non-Hodgkin lymphoma (40.1%), CNS tumors (32.8%), renal tumors (58.4%), bone tumors (33.4%), retinoblastoma (59.2%), and other solid tumors (52.6%). The 3-year overall survival rates varied among the regions; children between the east and south-southeast had the higher risks (hazard ratio 3.0; 95% CI: 2.3-3.9) and 2.4; 95% CI: 2.0-2.8) of death from disease when compared with those from the central region.

CONCLUSION

FPGC has increased coverage of cancer cases. Survival rates were different throughout the country. It is necessary to evaluate the effectiveness of this policy to increase access and identify opportunities to reduce the differences in survival.

ATP Binding Cassette C1 (ABCC1/MRP1)-mediated drug efflux contributes to disease progression in T-lineage acute lymphoblastic leukemia

PURPOSE

In acute lymphoblastic leukemia (ALL), multidrug resistance is often mediated by ATPase Binding Cassette (ABC) proteins, which principally involve ABCB1 (multidrug resistance 1, MDR1) and ABCC1 (multidrug resistance protein 1, MRP1). However, direct comparisons between the differential effects of ABCB1 and ABCC1 have been difficult, since identical cell lines with differential expression of these transporters have not been developed.

EXPERIMENTAL DESIGN

In this study, we developed and compared the biological profiles of Jurkat cell lines that selectively over-expressed ABCB1 and ABCC1. Vincristine (VCR) plays an important role in the treatment of T-lineage ALL (T-ALL), and is often the first drug given to newly-diagnosed patients. Because of its importance in treatment, we provided escalating, sub-lethal doses of VCR to Jurkat cells, and extended our observations to expression profiling of newly diagnosed patients with T-ALL.

RESULTS

We found that VCR-resistant cells over-expressed ABCC1 nearly 30-fold. The calcein AM assay confirmed that VCR-resistant cells actively extruded VCR, and that ABCC1-mediated drug resistance conferred a different spectrum of multidrug resistance than other T-ALL induction agents. siRNA experiments that blocked ABCC1 export confirmed that VCR resistance could be reversed in vitro. Analyses of T-lymphoblasts obtained from 92 newly diagnosed T-ALL patients treated on Children's Oncology Group Phase III studies 8704/9404 showed that induction failure could be explained in all but one case by the over-expression of ABCB1 or ABCC1.

CONCLUSIONS

Taken together, these results suggest that over-expression of ABC transporters plays a contributing role in mediating treatment failure in T-ALL, and underscore the need to employ alternate treatment approaches in patients for whom induction failed or for those with relapsed disease.

Weekend delay in initiation of chemotherapy for acute lymphoblastic leukemia: does it matter?

The Friday afternoon admission of a child with a potential diagnosis of leukemia creates perceived delays in treatment initiation. Although generally not felt to affect prognosis, the effect of a few days delay in chemotherapy for children with acute lymphoblastic leukemia (ALL) has not been fully investigated. We retrospectively analyzed 207 patients consecutively diagnosed with ALL at Children's Hospital & Research Center Oakland from 1995 to 2007 to determine if delay in chemotherapy increased the risk of relapse, death, transfer to the intensive care unit, or bacteremia. Friday admission did not significantly delay chemotherapy initiation with treatment started at a mean of 4.13±2.40 days for Friday admits versus 3.72±1.57 days for all others (P=0.29). There was no significant association between treatment delay days and relapse (P=0.94) or death (P=0.55). In Cox regression analysis, treatment delay was not a predictor of time to relapse (P=0.80) or longer duration of hospitalization (corrected for delay, P=0.15). There were trends toward significant associations between treatment delay and bacteremia (P=0.07) and intensive care unit admissions (P=0.08), although both were associated with shorter, not longer, treatment delays.We were unable to demonstrate a significant effect of delay in chemotherapy initiation for pediatric patients with newly diagnosed ALL on the examined outcome variables.

Inducing apoptosis in chemotherapy-resistant B-lineage acute lymphoblastic leukaemia cells by targeting HSPA5, a master regulator of the anti-apoptotic unfolded protein response signalling network

We present previously unknown evidence that the immunoglobulin heavy chain binding protein BIP/HSPA5, also known as glucose regulated protein (GRP)78, serving as a pivotal component of the pro-survival axis of the unfolded protein response (UPR) signalling network, is abundantly expressed in relapsed B-lineage acute lymphoblastic leukaemia (ALL) and contributes to chemotherapy resistance of leukaemic B-cell precursors. The resistance of B-lineage ALL cells to the standard anti-leukaemic drug vincristine was overcome by the HSPA5 inhibitor epigallocatechin gallate, which inhibits the anti-apoptotic function of HSPA5 by targeting its ATP-binding domain. Notably, chemotherapy-resistant B-lineage ALL cells underwent apoptosis within 48 h of exposure to a doxorubicin-conjugated cell-penetrating cyclic anti-HSPA5 peptide targeting surface-expressed HSPA5 molecules on leukaemia cells. The identification of the HSPA5 as a chemoresistance biomarker and molecular target for B-lineage ALL may lead to new anti-leukaemic treatment strategies that are much needed.

Postrelapse survival in childhood acute lymphoblastic leukemia is independent of initial treatment intensity: a report from the Children's Oncology Group

While intensification of therapy has improved event-free survival (EFS) and survival in newly diagnosed children with acute lymphoblastic leukemia (ALL), postrelapse outcomes remain poor. It might be expected that patients relapsing after inferior initial therapy would have a higher retrieval rate than after superior therapy. In the Children's Oncology Group Study CCG-1961, significantly superior EFS and survival were achieved with an augmented (stronger) versus standard intensity regimen of postinduction intensification (PII) for children with newly diagnosed high-risk ALL and rapid day 7 marrow response (EFS/survival 81.2%/88.7% vs 71.7%/83.4%, respectively). This provided an opportunity to evaluate postrelapse survival (PRS) in 272 relapsed patients who had received randomly allocated initial treatment with augmented or standard intensity PII. As expected, PRS was worse for early versus late relapse, marrow versus extramedullary site, adolescent versus younger age and T versus B lineage. However, no difference in 3-year PRS was detected for having received augmented versus standard intensity PII (36.4% ± 5.7% vs 39.2% ± 4.1%; log rank P = .72). Similar findings were noted within subanalyses by timing and site of relapse, age, and immunophenotype. These findings provide insight into mechanisms of relapse in ALL, and are consistent with emergence of a resistant subclone that has acquired spontaneous mutations largely independent of initial therapy. This study is registered at www.clinicaltrials.gov as NCT00002812.

Twenty-five years of treatment for childhood acute lymphoblastic leukaemia in Western Australia: how do we compare?

OBJECTIVES

To compare survival among the subgroup of children with acute lymphoblastic leukaemia (ALL) who were treated at Princess Margaret Hospital for Children (PMH) in Perth, Western Australia, over 25 years under 15 consecutive protocols of the Children's Cancer Group (CCG) with survival for the entire cohort of children in multiple centres treated under CCG protocols in that period; and to highlight the benefits of membership of a large cooperative research group conducting multicentre randomised controlled trials.

DESIGN, PARTICIPANTS AND SETTING

Retrospective review of the outcomes of all 311 children with newly diagnosed ALL treated at PMH between 1983 and 2008.

MAIN OUTCOME MEASURES

4-year event-free survival; and 10-year overall survival.

RESULTS

Four-year event-free survival for the entire PMH cohort increased from 66% (SE, 6%) for 1983-1987 to 88% (SE, 6%) for 2002-2005, while overall survival over the same period improved from 78% (SE, 5%) to 94% (SE, 4%). Comparisons of outcomes of children treated at PMH with those of the entire CCG cohort, protocol by protocol, revealed similar outcomes.

CONCLUSION

Outcomes of children treated at PMH over the 25-year period are equivalent to those of the larger CCG cohort.

CD22 EXON 12 deletion as a pathogenic mechanism of human B-precursor leukemia

Here, we report that primary leukemic cells from infants with newly diagnosed B-precursor leukemia express a truncated and functionally defective CD22 coreceptor protein that is unable to transmit apoptotic signals because it lacks most of the intracellular domain, including the key regulatory signal transduction elements and all of the cytoplasmic tyrosine residues. Expression of this structurally and functionally abnormal CD22 protein is associated with a very aggressive in vivo growth of patients' primary leukemia cells causing disseminated overt leukemia in SCID mice. The abnormal CD22 coreceptor is encoded by a profoundly aberrant mRNA arising from a splicing defect that causes the deletion of exon 12 (c.2208-c.2327) (CD22ΔE12) and results in a truncating frameshift mutation. The splicing defect is associated with multiple homozygous mutations within a 132-bp segment of the intronic sequence between exons 12 and 13. These mutations cause marked changes in the predicted secondary structures of the mutant CD22 pre-mRNA sequences that affect the target motifs for the splicing factors hnRNP-L, PTB, and PCBP that are up-regulated in infant leukemia cells. Forced expression of the mutant CD22ΔE12 protein in transgenic mice perturbs B-cell development, as evidenced by B-precursor/B-cell hyperplasia, and corrupts the regulation of gene expression, causing reduced expression levels of several genes with a tumor suppressor function. We further show that CD22ΔE12-associated unique gene expression signature is a discriminating feature of newly diagnosed infant leukemia patients. These striking findings implicate CD22ΔE12 as a previously undescribed pathogenic mechanism in human B-precursor leukemia.

Cognitive Sparing during the Administration of Whole Brain Radiotherapy and Prophylactic Cranial Irradiation: Current Concepts and Approaches

Whole brain radiotherapy (WBRT) for the palliation of metastases, or as prophylaxis to prevent intracranial metastases, can be associated with subacute and late decline in memory and other cognitive functions. Moreover, these changes are often increased in both frequency and severity when cranial irradiation is combined with the use of systemic or intrathecal chemotherapy. Approaches to preventing or reducing this toxicity include the use of stereotactic radiosurgery (SRS) instead of WBRT; dose reduction for PCI; exclusion of the limbic circuit, hippocampal formation, and/or neural stem cell regions of the brain during radiotherapy; avoidance of intrathecal and/or systemic chemotherapy during radiotherapy; the use of high-dose, systemic chemotherapy in lieu of WBRT. This review discusses these concepts in detail as well as providing both neuroanatomic and radiobiologic background relevant to these issues.