Proton Therapy Mediates Dose Reductions to Brain Structures Associated With Cognition in Children With Medulloblastoma

PURPOSE

Emerging evidence suggests proton radiation therapy may offer cognitive sparing advantages over photon radiation therapy, yet dosimetry has not been compared previously. The purpose of this study was to examine dosimetric correlates of cognitive outcomes in children with medulloblastoma treated with proton versus photon radiation therapy.

METHODS AND MATERIALS

In this retrospective, bi-institutional study, dosimetric and cognitive data from 75 patients (39 photon and 36 proton) were analyzed. Doses to brain structures were compared between treatment modalities. Linear mixed-effects models were used to create models of global IQ and cognitive domain scores.

RESULTS

The mean dose and dose to 40% of the brain (D40) were 2.7 and 4.1 Gy less among proton-treated patients compared with photon-treated patients (P = .03 and .007, respectively). Mean doses to the left and right hippocampi were 11.2 Gy lower among proton-treated patients (P < .001 for both). Mean doses to the left and right temporal lobes were 6.9 and 7.1 Gy lower with proton treatment, respectively (P < .001 for both). Models of cognition found statistically significant associations between higher mean brain dose and reduced verbal comprehension, increased right temporal lobe D40 with reduced perceptual reasoning, and greater left temporal mean dose with reduced working memory. Higher brain D40 was associated with reduced processing speed and global IQ scores.

CONCLUSIONS

Proton therapy reduces doses to normal brain structures compared with photon treatment. This leads to reduced cognitive decline after radiation therapy across multiple intellectual endpoints. Proton therapy should be offered to children receiving radiation for medulloblastoma.

Genetic susceptibility to cognitive decline following craniospinal irradiation for pediatric central nervous system tumors

BACKGROUND

Survivors of pediatric central nervous system (CNS) tumors treated with craniospinal irradiation (CSI) exhibit long-term cognitive difficulties. Goals of this study were to evaluate longitudinal effects of candidate and novel genetic variants on cognitive decline following CSI.

METHODS

Intelligence quotient (IQ), working memory (WM), and processing speed (PS) were longitudinally collected from patients treated with CSI (n = 241). Genotype-by-time interactions were evaluated using mixed-effects linear regression to identify common variants (minor allele frequency > 1%) associated with cognitive performance change. Novel variants associated with cognitive decline (P < 5 × 10-5) in individuals of European ancestry (n = 163) were considered replicated if they demonstrated consistent genotype-by-time interactions (P < .05) in individuals of non-European ancestries (n = 78) and achieved genome-wide statistical significance (P < 5 × 10-8) in a meta-analysis across ancestry groups.

RESULTS

Participants were mostly males (65%) diagnosed with embryonal tumors (98%) at a median age of 8.3 years. Overall, 1150 neurocognitive evaluations were obtained (median = 5, range: 2-10 per participant). One of the five loci previously associated with cognitive outcomes in pediatric CNS tumors survivors demonstrated significant time-dependent IQ declines (PPARA rs6008197, P = .004). Two variants associated with IQ in the general population were associated with declines in IQ after Bonferroni correction (rs9348721, P = 1.7 × 10-5; rs31771, P = 7.8 × 10-4). In genome-wide analyses, we identified novel loci associated with accelerated declines in IQ (rs116595313, meta-P = 9.4 × 10-9), WM (rs17774009, meta-P = 4.2 × 10-9), and PS (rs77467524, meta-P = 1.5 × 10-8; rs17630683, meta-P = 2.0 × 10-8; rs73249323, meta-P = 3.1 × 10-8).

CONCLUSIONS

Inherited genetic variants involved in baseline cognitive functioning and novel susceptibility loci jointly influence the degree of treatment-associated cognitive decline in pediatric CNS tumor survivors.

Patient-reported neurocognitive function in adult survivors of childhood and adolescent osteosarcoma and Ewing sarcoma

PURPOSE

Little is known regarding long-term neurocognitive outcomes in osteosarcoma and Ewing sarcoma (EWS) survivors despite potential risk factors. We evaluated associations among treatment exposures, chronic health conditions, and patient-reported neurocognitive outcomes in adult survivors of childhood osteosarcoma and EWS.

METHODS

Five-year survivors of osteosarcoma (N = 604; median age 37.0 years) and EWS (N = 356; median age 35.0 years) diagnosed at < 21 years from 1970 to 1999, and 697 siblings completed the Childhood Cancer Survivor Study Neurocognitive Questionnaire and reported chronic health conditions, education, and employment. Prevalence of reported neurocognitive difficulties were compared between diagnostic groups and siblings. Modified Poisson regression identified factors associated with neurocognitive difficulties.

RESULTS

Osteosarcoma and EWS survivors, vs. siblings, reported higher prevalences of difficulties with task efficiency (15.4% [P = 0.03] and 14.0% [P = 0.04] vs. 9.6%, respectively) and emotional regulation (18.0% [P < 0.0001] and 15.2% [P = 0.03] vs. 11.3%, respectively), adjusted for age, sex, and ethnicity/race. Osteosarcoma survivors reported greater memory difficulties vs. siblings (23.5% vs. 16.4% [P = 0.01]). Comorbid impairment (i.e., ≥ 2 neurocognitive domains) was more prevalent in osteosarcoma (20.0% [P < 0.001]) and EWS survivors (16.3% [P = 0.02]) vs. siblings (10.9%). Neurological conditions were associated with worse task efficiency (RR = 2.17; 95% CI = 1.21-3.88) and emotional regulation (RR = 1.88; 95% CI = 1.01-3.52), and respiratory conditions were associated with worse organization (RR = 2.60; 95% CI = 1.05-6.39) for EWS. Hearing impairment was associated with emotional regulation difficulties for osteosarcoma (RR = 1.98; 95% CI = 1.22-3.20). Patient report of cognitive difficulties was associated with employment but not educational attainment.

CONCLUSIONS

Survivors of childhood osteosarcoma and EWS are at increased risk for reporting neurocognitive difficulties, which are associated with employment status and appear related to chronic health conditions that develop over time.

IMPLICATIONS FOR CANCER SURVIVORS

Early screening, prevention, and treatment of chronic health conditions may improve/prevent long-term neurocognitive outcomes.

Cognitive Sparing in Proton versus Photon Radiotherapy for Pediatric Brain Tumor Is Associated with White Matter Integrity: An Exploratory Study

Radiotherapy for pediatric brain tumors is associated with reduced white matter structural integrity and neurocognitive decline. Superior cognitive outcomes have been reported following proton radiotherapy (PRT) compared to photon radiotherapy (XRT), presumably due to improved sparing of normal brain tissue. This exploratory study examined the relationship between white matter change and late cognitive effects in pediatric brain tumor survivors treated with XRT versus PRT. Pediatric brain tumor survivors treated with XRT (n = 10) or PRT (n = 12) underwent neuropsychological testing and diffusion weighted imaging >7 years post-radiotherapy. A healthy comparison group (n = 23) was also recruited. Participants completed age-appropriate measures of intellectual functioning, visual-motor integration, and motor coordination. Tractography was conducted using automated fiber quantification (AFQ). Fractional anisotropy (FA), axial diffusivity (AD), and radial diffusivity (RD) were extracted from 12 tracts of interest. Overall, both white matter integrity (FA) and neuropsychological performance were lower in XRT patients while PRT patients were similar to healthy control participants with respect to both FA and cognitive functioning. These findings support improved long-term outcomes in PRT versus XRT. This exploratory study is the first to directly support for white matter integrity as a mechanism of cognitive sparing in PRT.

A Prospective Evaluation of Fatigue in Pediatric Brain Tumor Patients Treated With Radiation Therapy

Background: Fatigue is a well-established consequence of cranial radiotherapy in survivors of pediatric brain tumor, but less is known about acute fatigue during radiotherapy treatment. This study aimed to longitudinally evaluate fatigue in newly diagnosed pediatric patients with brain tumors during treatment. Methods: Primary caregivers of pediatric patients with brain tumors completed the proxy-reported Parent Fatigue Scale assessments prior to radiotherapy and weekly during radiotherapy treatment. The association between clinical factors and fatigue at each assessment was evaluated with multiple linear regressions. A comparison of fatigue between radiation modalities was also analyzed. Results: A total of 33 caregivers completed pre-radiation fatigue assessments, with 29 reporting fatigue during radiotherapy. Patients were aged 3 to 16 years (M = 8.32) at diagnosis and diagnosed with medulloblastoma (n = 23), primitive neuroectodermal tumor (n = 2), ependymoma (n = 1), germ cell tumor (n = 1), pineoblastoma (n = 1), atypical teratoid rhabdoid (n = 1), and other unspecific tumors (n = 3). Moderate-to-severe fatigue was reported for the majority of patients (31/33; 94%) during treatment. Craniospinal irradiation dose was the only significant predictor of fatigue (p < .05), but this association was restricted to the first week of therapy and was attenuated by therapy completion. Discussion: Although fatigue is often considered a long-term consequence of cranial radiotherapy, this pilot study demonstrates that moderate-to-severe fatigue is pervasive prior to radiotherapy and persists throughout treatment in pediatric patients with brain tumors, regardless of radiation modality or clinical factors. Additional research is warranted to establish a link between acute and long-term fatigue and develop interventions to mitigate this adverse outcome.

Pediatric rhabdomyosarcoma incidence and survival in the United States: An assessment of 5656 cases, 2001-2017

BACKGROUND

While rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children and adolescents, past epidemiology studies of this malignancy used data that covered <30% of the US population. Therefore, we evaluated RMS incidence using data from U.S. Cancer Statistics (USCS) and survival trends using the National Program of Cancer Registries (NPCR), which covers 100% and 94% of the U.S. population, respectively.

METHODS

Incidence and survival were assessed for pediatric patients diagnosed with RMS during 2003-2017 and 2001-2016, respectively. Both demographic and clinical variables were evaluated. Age-adjusted incidence rates, average annual percent change (AAPC), and 5-year relative survival (RS) were calculated, all with corresponding 95% confidence intervals (CIs). Cox regression models were used to evaluate the impact of demographic and clinical variables on survival.

RESULTS

We identified 5656 primary RMS cases in USCS during 2003-2017. The age-adjusted incidence rate was 4.58 per 1 million (95% CI: 4.46-4.70) with an AAPC of 0.3% (95% CI: -0.7 to 1.2%). In NPCR, 5-year RS for all cases was 68.0% (95% CI: 66.6-69.3%). In multivariable analyses, non-Hispanic (NH) Black cases had worse survival compared with NH White cases (hazard ratio [HR] = 1.16, 95% CI: 1.01-1.33).

CONCLUSION

The incidence and survival rates were stable in the largest and most comprehensive population-based analysis for pediatric RMS cases in the U.S. Additionally, we observed a survival disparity among NH Black cases. Findings from this study could inform interventions to address disparities, risk stratification strategies, and clinical trial design.

Scoliosis in Children Treated With Photon Craniospinal Irradiation for Medulloblastoma

PURPOSE

Scoliosis is a well-recognized complication after abdominal radiation therapy but not reported frequently after craniospinal irradiation (CSI). We examined the incidence and risk factors for scoliosis after CSI in long-term survivors with medulloblastoma.

METHODS AND MATERIALS

The records of patients with medulloblastoma seen at one institution from 1996 to 2006 were analyzed for the use of CSI and development of scoliosis as documented on physical examination and spinal imaging.

RESULTS

We identified 35 children with medulloblastoma who were ≤12 years of age at time of CSI with a median 14.3 years (range, 5.8-19.3 years) of follow-up. Twenty-seven (77.1%) were male, and median age at CSI was 6.8 years (range, 2.8-12 years). The cumulative incidence of scoliosis at 15 years was 34.6%. The median time to develop scoliosis was 7.1 years (range, 5-11.7 years) after CSI. Treatment with high dose CSI (34.2-40 Gy) and presence of hemiplegia or hemiparesis were found to be risk factors for development of scoliosis.

CONCLUSIONS

Scoliosis is an underreported complication of photon craniospinal irradiation.

Team sugar: Blood glucose screening in acute lymphoblastic leukemia patients during induction

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Background: Pediatric acute lymphoblastic leukemia (ALL) protocols currently include steroids during induction therapy, which may lead to hyperglycemia. Published pediatric and adult leukemia data demonstrate increased rates of infection and mortality associated with hyperglycemia. Presently, there are no accepted recommendations for how to track blood glucose (BG) levels, so hyperglycemia may go undetected. A random review of 20 patients diagnosed with ALL during a 4-month period in 2014 at Texas Children’s Cancer Center (TXCCC) demonstrated that only 40% had BG checked throughout induction. The SMART aim of this quality improvement project was to increase BG screening rates to > 95% during first week of treatment and induction days 8, 15, 22 and 29 for patients with newly diagnosed ALL at TXCCC in a 15-month period. Methods: PDSA cycle 1 involved sticker reminders on treatment roadmaps by days that required a BG check. PDSA cycle 2 entailed reminder flyers in patient care areas and no further roadmap stickers. Primary outcome measure was the percentage of successful occurrences for BG checks on days 8, 15, 22, 29. Secondary outcome measure was the percentage of patients who needed insulin therapy. Results: TXCCC had 97 new ALL patients during March 2015 to May 2016. Providers obtained 333 of 372 possible BG checks (90%) on days 8, 15, 22, 29. Thirty-nine percent of patients developed hyperglycemia ≥ 200 mg/dL. Eighteen percent patients required insulin therapy. Eighty-nine percent of patients had their peak blood glucose by day 8, and 82% of patients who required insulin were started on insulin prior to day 8. Conclusions: We improved hyperglycemia screening rates for TXCCC ALL patients in induction from 40% to 90% by implementing reminder processes for providers. The roadmap stickers were replaced with reminder flyers for sustainability. Because the peak BG was reached by 89% of patients by day 8 of therapy, our efforts are now being directed at improving screening and interventions prior to day 8. Our goal is to standardize BG screening and hyperglycemia intervention algorithms to decrease both the time-to-initiation for insulin and readmission rate for symptomatic hyperglycemia for ALL patients at TXCCC.

A childhood acute lymphoblastic leukemia genome-wide association study identifies novel sex-specific risk variants

Childhood acute lymphoblastic leukemia (ALL) occurs more frequently in males. Reasons behind sex differences in childhood ALL risk are unknown. In the present genome-wide association study (GWAS), we explored the genetic basis of sex differences by comparing genotype frequencies between male and female cases in a case-only study to assess effect-modification by sex.The case-only design included 236 incident cases of childhood ALL consecutively recruited at the Texas Children's Cancer Center in Houston, Texas from 2007 to 2012. All cases were non-Hispanic whites, aged 1 to 10 years, and diagnosed with confirmed B-cell precursor ALL. Genotyping was performed using the Illumina HumanCoreExome BeadChip on the Illumina Infinium platform. Besides the top 100 statistically most significant results, results were also analyzed by the top 100 highest effect size with a nominal statistical significance (P <0.05).The statistically most significant sex-specific association (P = 4 × 10) was with the single nucleotide polymorphism (SNP) rs4813720 (RASSF2), an expression quantitative trait locus (eQTL) for RASSF2 in peripheral blood. rs4813720 is also a strong methylation QTL (meQTL) for a CpG site (cg22485289) within RASSF2 in pregnancy, at birth, childhood, and adolescence. cg22485289 is one of the hypomethylated CpG sites in ALL compared with pre-B cells. Two missense SNPs, rs12722042 and 12722039, in the HLA-DQA1 gene yielded the highest effect sizes (odds ratio [OR] ∼ 14; P <0.01) for sex-specific results. The HLA-DQA1 SNPs belong to DQA1*01 and confirmed the previously reported male-specific association with DQA1*01. This finding supports the proposed infection-related etiology in childhood ALL risk for males. Further analyses revealed that most SNPs (either direct effect or through linkage disequilibrium) were within active enhancers or active promoter regions and had regulatory effects on gene expression levels.Cumulative data suggested that RASSF2 rs4813720, which correlates with increased RASSF2 expression, may counteract the suppressor effect of estrogen-regulated miR-17-92 on RASSF2 resulting in protection in males. Given the amount of sex hormone-related mechanisms suggested by our findings, future studies should examine prenatal or early postnatal programming by sex hormones when hormone levels show a large variation.

SOD2 genetic variant associated with treatment-related ototoxicity in cisplatin-treated pediatric medulloblastoma

Manganese superoxide dismutase (MnSOD), encoded by the SOD2 gene, is involved in the detoxification of superoxide anion. Superoxide is likely a source of oxidative stress in the cochlea following treatment with platinum agents and radiation. Therefore, we examined SOD2 variants in association with ototoxicity among cisplatin-treated childhood medulloblastoma patients. Blood samples were obtained from 71 eligible patients treated for pediatric medulloblastoma at Texas Children’s Cancer Center (1987–2010). Ototoxicity was defined as requiring the use of a hearing aid sometime after the initiation of therapy. DNA was genotyped on the Illumina HumanOmni-1 Quad BeadChip. A linkage disequilibrium (LD)-based single-nucleotide polymorphism (SNP) selection strategy was used to identify a minimal set of informative variants. Associations between SNPs and ototoxicity were assessed using logistic regression. Of the 71 eligible patients, 26 (37%) suffered from cisplatin-related ototoxicity. Study participants were primarily male (73%) and non-Hispanic white (42%). Five SOD2 variants (rs7855, rs5746151, rs5746136, rs2758331, and rs4880) identified by the LD-based selection strategy were genotyped. After correcting for multiple comparisons, the C-allele of the rs4880 variant was significantly associated with ototoxicity (odds ratio = 3.06, 95% confidence interval: 1.30–7.20) in adjusted models. The rs4880 T > C substitution results in a Val > Ala amino acid change at position 16 of the MnSOD mitochondrial targeting sequence. The Ala variant, which has been associated with increased MnSOD activity, was associated with hearing damage in this study. Platinum-based therapies increase the expression of MnSOD, which may result in an abundance of hydrogen peroxide, a reactive oxygen species. Therefore, oxidative stress may be an important mechanism in therapy-related cochlear damage.

Abstract 853: The role of germline microRNA-related polymorphisms on pediatric medulloblastoma prognosis and survival

Background: Five-year survival for pediatric medulloblastoma is between 60-80%, which remains far from ideal. While the molecular features of these tumors are being used to improve risk stratification, novel markers are needed to identify those at the greatest risk of recurrence and poor survival. MicroRNAs (miRNA) regulate gene expression and may play a major role in regulatory networks related to cancer therapy. Because of that, single nucleotide polymorphisms (SNPs) within these regions (miR-SNPs), which have the ability to alter normal miRNA function, are being evaluated in terms of cancer prognosis and survival. However, to our knowledge, miR-SNPs have not been evaluated in terms of outcomes (recurrence and survival) among those with pediatric medulloblastoma.

Methods: Patients with medulloblastoma (n = 100) treated at Texas Children's Cancer Center and MD Anderson Cancer Center between 1982 and 2009 who had existing genotype data from the Illumina Omni1 array were included in this analysis. We selected 25 miR-SNPs within 24 genes with a minor allele frequency (MAF) greater than 5%. Variants were selected from within pri- or pre-miRNAs, miRNA processing machinery, or within binding sites identified in the literature as related to tumorigenesis. The remaining variants were predicted to create or destroy miRNA binding sites per the prediction algorithm PolymiRTS 3.0. Adjusted hazard ratios (aHR) and 95% confidence intervals (CIs) were calculated using Cox regression under log-additive or dominant genetic models (if the MAF fell between 5-15%) to estimate the association between miR-SNPs and progression-free and overall survival (OS) times. All models were adjusted for sex (reference = male), race (reference = white), and age at diagnosis (continuous). Clinical variables including risk group, and craniospinal radiation were also analyzed. Multiple comparisons were adjusted for using the false discovery rate method.

Results: The median follow-up time among 88 survivors was 8.33 years (range 1.16 - 25.83 years). Individuals who carry a copy of the minor allele of KIAA0423 (rs1053667), which is located within a putative miR-19a/b binding site, experienced 2.93 times the hazard of progression (CC+CT vs. TT: aHR = 2.93; 95% CI: 1.10-7.83). For overall survival, carriers of a copy of the minor allele experienced 3.96 times the hazard of death (CC+CT vs. TT: aHR = 3.96; 95% CI: 1.12-14.02). While these data point to a potentially strong effect, the results did not remain significant after adjustment for multiple comparisons.

Conclusions: This preliminary analysis suggests that certain miR-SNPs may be associated with pediatric medulloblastoma recurrence and survival; however our findings must be validated in a larger population. Validated miR-SNPs may potentially be used for refined risk stratification for those diagnosed with childhood cancers or may be informative for targeted therapies.

Citation Format: Erin C. Peckham, Philip J. Lupo, Austin L. Brown, Mehmet Fatih Okcu, Ching C. Lau, Surya Rednam, Michael E. Scheurer. The role of germline microRNA-related polymorphisms on pediatric medulloblastoma prognosis and survival. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 853. doi:10.1158/1538-7445.AM2015-853

Clinical and Genetic Predictors of Impaired Fertility in Female Survivors of Childhood Cancer

An important late effect among female survivors of childhood cancer is treatment-related ovarian damage and impaired fertility. While chemotherapy and radiation therapy are associated with impaired fertility, few other risk factors have been identified. Furthermore, little is known about the role of genetic susceptibility to these late effects. Objective: As Anti-Müllerian Hormone (AMH) is a demonstrated marker of ovarian reserve; our objective was to identify clinical and genetic predictors of AMH levels in female survivors of childhood cancer. Methods: Female childhood cancer survivors (n = 181) were recruited from the Texas Children's Cancer Center Long Term Survivor Program (LTSP). AMH (ng/mL) was measured using an enzyme-linked immunosorbent assay. Information on age at diagnosis and enrollment, race, ethnicity, cancer diagnosis, pelvic radiation, and use of alkylating agents was abstracted from medical records. The following single nucleotide polymorphisms (SNPs) were selected based on known or suspected function: AMHR2 rs2002555; CYP2C9*4 rs56165452; CYP2C19*2 rs4244285; and CYP2C19*3 rs4986893. SNPs were genotyped using TaqMan assays. Linear regression was used to determine the association between selected factors and AMH levels. As AMH levels were not normally distributed, the dependent variable was expressed as log10(AMH+1). Results: The mean age at enrollment in the LTSP was 12.4 years. The most common cancer diagnosis was acute lymphoblastic leukemia (47.2%), and a substantial proportion of the population was Hispanic (41.0%). The following variables were significantly associated with lower AMH levels: pelvic radiation (beta = −0.61, P &lt; 0.001) and treatment with alkylating agents (beta = −0.09, P = 0.04). Age at enrollment was associated with higher AMH levels (beta = 0.01, P = 0.04). Hispanic ethnicity was marginally associated with lower AMH levels (beta = −0.08, P = 0.08). There were no significant genetic associations. Conclusions: In one of the largest studies of its kind, our results confirm previous associations between treatment-related factors and ovarian damage. While the SNPs evaluated were not predictive of AMH levels, more work is needed to explain why some survivors experience impaired fertility, while others do not, despite similar therapy.

Glutathione S-transferase P1 single nucleotide polymorphism predicts permanent ototoxicity in children with medulloblastoma

BACKGROUND

Glutathione S-transferase (GST) enzymes are involved in detoxifying chemotherapy and clearing reactive oxygen species formed by radiation. We explored the relationship between the host GSTP1 105 A > G polymorphism (rs1695), tumor GSTpi protein expression, and clinical outcomes in pediatric medulloblastoma. We hypothesized that the GSTP1 105 G-allele and increased tumor GSTpi expression would be associated with lower progression-free survival and fewer adverse events.

PROCEDURE

The study included 106 medulloblastoma/primitive neuroectodermal tumor (PNET) patients seen at Texas Children's Cancer Center. Genotyping was performed using an Illumina HumanOmni1-Quad BeadChip and GSTpi expression was assessed using immunohistochemistry. We used the Kaplan-Meier method for survival analyses and logistic regression for toxicity comparisons.

RESULTS

Patients with a GSTP1 105 AG/GG genotype (vs. AA) or who had received high dose craniospinal radiation (≥34 Gy vs. <26 Gy) had a greater risk of requiring hearing aids than their counterparts (OR 4.0, 95% CI 1.2-13.6, and OR 3.1, 95% CI 1.1-8.8, respectively, n = 69). Additionally, there was a statistically significant interaction between these variables. Compared with the lowest risk group (GSTP1 105 AA-low dose radiation), patients with a GSTP1 105 AG/GG genotype who received high dose radiation were 8.4 times more likely to require hearing aids (95% CI 1.4-49.9, p-trend = 0.005, n = 69). When adjusted for age, cumulative cisplatin dose, and amifostine use, the association remained.

CONCLUSIONS

The GSTP1 105 G-allele is associated with permanent ototoxicity in pediatric medulloblastoma/PNET and strongly interacts with radiation dose. Patients with this allele should be considered for clinical trials employing radiation dose modifications and cytoprotectant strategies.

Dual-specificity phosphatase 26 is a novel p53 phosphatase and inhibits p53 tumor suppressor functions in human neuroblastoma

Chemoresistance is a major cause of treatment failure and poor outcome in neuroblastoma. In this study, we investigated the expression and function of dual-specificity phosphatase 26 (DUSP26), also known as mitogen-activated protein kinase phophatase-8, in human neuroblastoma. We found that DUSP26 was expressed in a majority of neuroblastoma cell lines and tissue specimens. Importantly, we found that DUSP26 promotes the resistance of human neuroblastoma to doxorubicin-induced apoptosis by acting as a p53 phosphatase to downregulate p53 tumor suppressor function in neuroblastoma cells. Inhibiting DUSP26 expression in the IMR-32 neuroblastoma cell line enhanced doxorubicin-induced p53 phosphorylation at Ser20 and Ser37, p21, Puma, Bax expression as well as apoptosis. In contrast, DUSP26 overexpression in the SK-N-SH cell line inhibited doxorubicin-induced p53 phosphorylation at Ser20 and Ser37, p21, Puma, Bax expression and apoptosis. Using in vitro and in vivo assays, we found that DUSP26 binds to p53 and dephosphorylates p53 at Ser20 and Ser37. In this report, we show that DUSP26 functions as a p53 phosphatase, which suppresses downstream p53 activity in response to genotoxic stress. This suggests that inhibition of this phosphatase may increase neuroblastoma chemosensitivity and DUSP26 is a novel therapeutic target for this aggressive pediatric malignancy.

Flow cytometry and fluorescence in situ hybridization to detect residual neuroblastoma cells in bone marrow

BACKGROUND

In patients with neuroblastoma morphological assessment of BM for residual NB cells is not precise, particularly when the number of tumor cells is small.

PROCEDURE

To develop a sensitive and rapid method of detecting NB cells in BM, we assessed the efficiency of flow cytometry (FCM) using markers CD9, CD56, and CD45. The percent of CD9+/CD56+/CD45- (NB phenotype) cells was determined by FCM in 41 samples (16 patients) at various time points. For confirmation fluorescence in situ hybridization (FISH) for 17q gain was performed.

RESULTS

Nineteen of the 22 (86%) samples that were negative by morphology were positive by FCM (>0.006% CD9+/CD56+/CD45- cells). The longest time to complete the FCM study was 3 hr. In six FISH experiments the sorted CD9+/CD56+/CD45- population had a higher percentage of cells with 17q gain (11.5-95%) compared to a CD56-/CD45+ internal control population (2-8%).

CONCLUSIONS

Our preliminary results suggest that FCM determination of the percent of CD9+/CD56+/CD45- cells is an effective method of rapidly detecting NB cells in BM.

Synovial sarcoma of childhood and adolescence: a multicenter, multivariate analysis of outcome

PURPOSE

To identify prognostic factors related to outcome in 219 children and adolescents with synovial sarcoma.

PATIENTS AND METHODS

We combined the experiences of the four following research groups: Cooperative Weichteilsarkomastudie Group, Germany (n = 95); St. Jude Children's Research Hospital, Memphis, TN (n = 49); Istituto Nazionale dei Tumori, Milan, Italy (n = 33); and The University of Texas M.D. Anderson Cancer Center, Houston, TX (n = 42). Kaplan-Meier and Cox proportional hazard analyses were performed.

RESULTS

The median age at diagnosis was 13 years (range, 1 to 20 years), and the median follow-up was 6.6 years (range, 0.5 to 30.7 years). The estimated 5-year overall survival and event-free survival rates for the entire group were 80% +/- 3% (SE) and 72% +/- 3%, respectively. A previously unreported interaction between tumor size and invasiveness was observed that statistically significantly related to outcome. In multivarible analysis, patients with T1B and T2B disease (hazard ratio [HR] = 5.6, 95% confidence interval (CI), 1.9 to 16.2; and HR = 5.9, 95% CI, 2.1 to 16.4, respectively) or Intergroup Rhabdomyosarcoma Study (IRS) Clinical Group III and IV disease (HR = 2.7, 95% CI, 1.2 to 6.5; and HR = 14.1, 95% CI, 4.3 to 31.3, respectively) had poor overall survival. Treatment with radiotherapy was related to improved overall survival (HR = 0.4; 95% CI, 0.2 to 0.7). In IRS Group III patients, objective response to chemotherapy (18 of 30, 60%) correlated with improved survival.

CONCLUSION

Clinical group, tumor size, and invasiveness are important prognostic factors. Multicenter randomized clinical trials are needed to determine both the effect of chemotherapy on survival and the necessity of local radiotherapy in patients with completely resected tumors.

Synovial sarcoma in children and adolescents: thirty three years of experience with multimodal therapy

BACKGROUND

Synovial sarcoma (SS) is the most common type of non-rhabdomyosarcoma soft tissue sarcoma in childhood, with controversies about its prognosis and treatment.

PROCEDURE

We reviewed medical records of 42 children and adolescents with SS treated at our institution between 1966 and 1999 to determine treatment results and assess prognostic factors.

RESULTS

With a median follow-up duration of 7.8 years (range 0.2-22.4 years), 5-year progression free survival (PFS) and overall survival (OS) rates were 75.6% (95% Confidence Interval [CI] 62-89.2%) and 87.7% (95% CI 77.3-98.1%) respectively. Eleven patients were dead and four others had progressed but were alive without evidence of disease after further therapy. IRS grouping and tumor invasiveness were found to be significant prognostic indicators (P < 0.01 and = 0.02, respectively). Patients with initial gross total resection (IRS I and II) and non-invasive tumors (T1) were most likely to have prolonged PFS and OS. Patients with small tumors (< 5 cm) (P = 0.09) or with monophasic histology (P = 0.14) had better PFS and OS.

CONCLUSIONS

Achieving a complete resection or gross total resection with microscopic residual disease is vital for survival of patients with localized SS. Patients with localized disease who received radiotherapy had improved local control. Chemotherapy did not seem to impact PFS or OS. Future large multi-institutional trials are needed to address whether post-operative chemotherapy is necessary for patients with localized, surgically removed tumors, whether radiotherapy is necessary for patients with completely resected tumors, and to ascertain the order of importance of all the candidate prognostic markers. Med Pediatr Oncol 2001;37:90-96.

Synovial sarcoma in children: surgical lessons from a single institution and review of the literature

BACKGROUND

Synovial sarcomas are malignant high-grade, soft-tissue neoplasms that account for 7% to 8% of all malignant soft-tissue tumors and are the most common nonrhabdomyosarcoma soft-tissue sarcomas in pediatric patients.

STUDY DESIGN

A retrospective review of the records of children younger than 17 years with synovial sarcoma treated at the University of Texas MD Anderson Cancer Center from 1966 until 1999 was undertaken. Primary site, tumor size, tumor margins, surgical treatment, adjuvant therapy, local and distant recurrence, and survival were recorded for 42 patients. Overall survival (OS) and progression-free survival (PFS) rates were calculated by the Kaplan-Meier method. The PFS and OS comparisons were performed using the log-rank test.

RESULTS

Forty-four patients were identified, but two patients were excluded because of incomplete records. The median followup duration for the 42 patients was 8.8 years (range 0.2 to 22.4 years). The 5-year progression-free survival and overall survival rates were 75.6% and 87.7%, respectively. Eleven patients were dead and four others had progressed but were alive without evidence of disease after further therapy. Intergroup Rhabdomyosarcoma Study (IRS) grouping and tumor invasiveness were found to be significant prognostic indicators (p < 0.01 and p = 0.02, respectively). Patients with initial gross total resection (IRS Groups I and II) and noninvasive tumors (T1) were most likely to have prolonged PFS and OS. Patients with small tumors (<5 cm) (p = 0.09) had better PFS and OS. Adjuvant radiation therapy appeared to be of benefit, and chemotherapy did not seem to impact PFS or OS. Tumors > or = 5 cm are associated with increased risk of local recurrence and distant metastases.

CONCLUSIONS

Complete resection with clear, yet not necessarily large, margins remains the treatment of choice for synovial sarcoma in children. Adjuvant radiation therapy should possibly be considered in patients with clear margins (IRS Group I) and in patients with microscopic residual tumor (IRS Group II). Chemotherapy did not seem to impact PFS or OS. Lymph nodes should be evaluated for local regional disease.

Expression of Bcl-2-related genes in normal and AML progenitors: changes induced by chemotherapy and retinoic acid

The expression of Bcl-2 family members was examined in normal and leukemic hematopoietic cells. Immature hematopoietic progenitor cells (CD34+/33-/13-) did not express Bcl-2 but Bcl-XL, the majority of CD34 cells expressed Bcl-2, Bcl-XL and BAD, and normal promyelocytes (CD34-/33+) lacked expression of both Bcl-2 and Bcl-XL, while leukemic CD34+progenitors and promyelocytes expressed these anti-apoptotic proteins. In AML, Bcl-2 expression was higher on CD34+ than on all AML cells, however, expression of Bcl-2 or Bcl-XL did not predict achievement of complete remission. Surprisingly, low Bcl-2 content was associated with poor survival in a group of patients with poor prognosis cytogenetics. The anti-apoptotic BAD protein was found to be expressed in AML, but was phosphorylated in 41/42 samples. Phosphorylation was found at both sites, Ser 112 and Ser 136. During induction chemotherapy, Bcl-2 levels of CD34 cells increased significantly. In the context of evidence for small numbers of leukemic CD34+ cells expressing very high levels of Bcl-2 prior to therapy, this finding is interpreted as a survival advantage of Bcl-2 overexpressing progenitors and rapid elimination of cells with low Bcl-2. Bcl-2 and Bcl-XL were both expressed in minimal residual disease cells. Downregulation of Bcl-2 mRNA and protein was observed by ATRA and the combination of Ara-C, followed by ATRA, resulted in markedly increased cytotoxicity in HL-60 cells, as compared to Ara-C alone or ATRA followed by Ara-C. Implications of these findings for the development of new therapeutic strategies for AML are discussed.

Differential increase of Fas ligand expression on metastatic and thin or thick primary melanoma cells compared with interleukin-10

Fas ligand (FasL), a cell surface molecule belonging to the tumour necrosis factor family, binds to its receptor Fas and thus induces apoptosis of Fas-bearing cells such as activated lymphocytes. In this paper, we report the expression of FasL on melanoma cell lines and patient tumour specimens, and compare it with the expression of interleukin-10 (IL-10), a putative immunosuppressive factor. Apoptosis of Fas-bearing Jurkat cells was increased after interferon-alpha treatment of the FasL-positive melanoma cell line A375, suggesting a regulation of FasL function. We also tested whether FasL and IL-10 were ever co-expressed. Immunohistochemistry studies showed that IL-10 expression was highly positive in the same tumour samples which expressed FasL. In the melanoma patients with thin primaries, 10 of the 12 primaries and six of the seven metastatic lesions were positive for IL-10. In the melanoma patients with thick primaries (> 0.75 mm), four of the five primary lesions and nine of the 10 metastatic lesions were positive for IL-10. In contrast, FasL was generally negative in primary tumours and positive in metastatic tumours. In the thin primary melanoma patients, two of the 12 primaries and five of the seven metastatic tumours were positive for FasL. From the thick melanomas, one of the five primaries and five of the 10 metastatic lesions were positive for FasL. The function of melanoma-derived FasL was confirmed by four different cytotoxicity assays.

Attenuation of WAF1/Cip1 expression by an antisense adenovirus expression vector sensitizes glioblastoma cells to apoptosis induced by chemotherapeutic agents 1,3-bis(2-chloroethyl)-1-nitrosourea and cisplatin

Previous studies have shown that the negative cell cycle regulator WAF1/Cip1 is often overexpressed in human gliomas and that WAF1/Cip1 overexpression renders glioma cells resistant to chemotherapy agents. In this study, we investigated whether down-regulation of WAF1/Cip1 would sensitize gliomas to chemotherapy. An adenoviral vector expressing antisense WAF1/Cip1 was constructed and used to infect D54 glioma cells, which express a high level of endogenous WAF1/Cip1. After D54 cells were infected with antisense WAF1/Cip1 adenovirus, Western blotting revealed a significant decrease in the WAF1/Cip1 protein level. Down-regulation of WAF1/Cip1 alone resulted in the cells rounding up and detaching from plates. Electron microscopy revealed some nuclear fragmentation in antisense WAF1/Cip1-infected cells, indicating the initiation of apoptosis. The antisense WAF1/Cip1-infected cells were then treated with the chemotherapeutic agents 1,3-bis(2-chloroethyl)-1-nitrosourea and cisplatin. Other cells were infected with sense WAF1/Cip1 adenovirus or control virus and served as controls. Trypan blue exclusion assay revealed significant cell death in antisense WAF1/Cip1-infected cells. In situ end-labeling assay by flow cytometry revealed that many cells died of apoptosis. Our results show that the attenuation of WAF1/Cip1 expression initiated glioma cell death and sensitized glioma cells to apoptosis induced by 1,3-bis(2-chloroethyl)-1-nitrosourea and cisplatin. Thus, blocking WAF1/Cip1 production may serve as a useful chemosensitization regimen for treating glioma.

Overexpressed WAF1/Cip1 renders glioblastoma cells resistant to chemotherapy agents 1,3-bis(2-chloroethyl)-1-nitrosourea and cisplatin

Previous studies have shown that the negative cell cycle regulator WAF1/Cip1 is often overexpressed in human gliomas and that WAF1/Cip1 overexpression may be a factor in cancer chemoresistance. We established a doxycycline-inducible WAF1/Cip1 expression system in two glioblastoma cell lines and examined the role of WAF1/Cip1 in their response to the chemotherapy agents 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) and cis-diamminedichloroplatinum (cisplatin), in an isogeneic background. Our results showed that the induction of WAF1/Cip1 expression rendered glioma cells resistant to cell death induced by BCNU and cisplatin. Using an in vivo host-cell reactivation DNA repair assay, we demonstrated that WAF1/Cip1 enhances the repair of BCNU-induced DNA damage. We conclude that WAF1/Cip1 allows repair of BCNU- and cisplatin-damaged DNA and protects glioma cells from chemotherapy agent-induced apoptosis. Thus, blocking WAF1/Cip1 production or function may serve as a useful chemosensitization regimen for glioma.