Mehmet Fatih Okcu

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 Childrens 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.

Risk analysis of severe myelotoxicity with temozolomide: The effects of clinical and genetic factors

A benefit of temozolomide (TMZ) is that myelotoxicity is uncommon. Recently, several small series have reported significant myelotoxicity resulting in treatment delays or death. The ability to predict risk of myelotoxicity may influence patient care. We retrospectively reviewed 680 malignant glioma patients and developed a clinical risk formula for myelotoxicity for each gender by logistic regression. The variables that remained were assigned a score of 1 and added together for a final risk score. Women experienced more myelotoxicity than did men (p = 0.015). For males, risk factors included body surface area (BSA) > or = 2 m(2) (odds ratio [OR] = 2.712, p = 0.04), not on steroids (OR = 2.214, p = 0.06), and on bowel medication (OR = 3.955, p = 0.008). For females, final factors included no prior chemotherapy (OR = 3.727, p = 0.001), creatinine > or = 1 mg/dl (OR = 6.08, p = 0.002), platelets < 270,000/mm(3) (OR = 2.438, p = 0.03), BSA < 2 m(2) (OR = 4.178, p = 0.04), not on medication for gastroesophageal reflux disease (OR = 2.942, p = 0.01), and on analgesics (OR = 2.169, p = 0.05). Age was included because of observable trends. Risk of developing myelotoxicity ranged from 0% to 33% (male) and from 0% to 100% (females). Polymorphisms in NQO1 (NAD(P)H dehydrogenase, quinone 1), MGMT (O(6)-methylguanine-DNA methyltransferase), and GSTP1 (glutathione S-transferase pi 1) were related to risk of developing myelotoxicity in a subset of patients. Myelotoxicity with TMZ is a significant clinical issue for those at risk. Use of a clinical model to predict risk and evaluation of identified genetic polymorphisms related to myelotoxicity may allow for individualized dosing, optimizing patient management.

Long-term disease control and toxicity outcomes following surgery and intensity modulated radiation therapy (IMRT) in pediatric craniopharyngioma

PURPOSE To report long-term progression-free survival (PFS) and late-toxicity outcomes in pediatric craniopharyngioma patients treated with IMRT. PATIENTS AND METHODS Twenty-four children were treated with IMRT to a median dose of 50.4Gy (range, 49.8-54Gy). The clinical target volume (CTV) was the gross tumor volume (GTV) with a 1cm margin. The planning target volume (PTV) was the CTV with a 3-5mm margin. Median follow-up was 107.3months. RESULTS The 5- and 10-year PFS rates were 65.8% and 60.7%. The 5- and 10-year cystic PFS rates were 70.2% and 65.2% while the 5- and 10-year solid PFS were the same at 90.7%. Endocrinopathy was seen in 42% at initial diagnosis and in 74% after surgical intervention, prior to IMRT. Hypothalamic dysfunction and visual deficits were associated with increasing PTV and number of surgical interventions. CONCLUSIONS IMRT is a viable treatment option for pediatric craniopharyngioma. Despite the use of IMRT, majority of the craniopharyngioma patients experienced long-term toxicity, many of which present prior to radiotherapy. Limitations of retrospective analyses on small patient cohort elicit the need for a prospective multi-institutional study to determine the absolute benefit of IMRT in pediatric craniopharyngioma.

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 Childrens 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.

Neuroendocrine Tumor of the Appendix in Children

Neuroendocrine tumor (NET) of the appendix is the most common gastrointestinal epithelial tumor in children. The utility of serum markers or the indication for hemicolectomy has not been established in children. In 45 children diagnosed with appendiceal NET, 89% NETs were incidentally found following appendectomy performed for suspected acute appendicitis. The median age was 12 years, and 56% patients were female. Postoperative somatostatin scan (n=5), serum chromogranin A (n=4), and urine 5-HIAA (n=9) were all within normal limits. Pathology slides of 35 patients showed mesoappendiceal invasion in 29% patients, and vascular invasion in 6% patients. Seven patients (16%) underwent hemicolectomy for invasion of mesoappendix (n=5), tumor near the resection margin (n=1), and tumor size 1.5 cm with vascular invasion (n=1). Only 2 hemicolectomy specimens showed disease: one in the appendiceal stump and the other as a micrometastasis in a mesenteric lymph node. There were no recurrences and all patients were alive and without evidence of disease at last follow-up. Pediatric appendiceal NET tends to have a benign clinical course with excellent prognosis. In the absence of carcinoid syndrome, postoperative scans and serum biomarkers do not seem to be useful. With completely resected tumors, the indication for hemicolectomy is unclear.

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

AbstractChildhood 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 Childrens 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 × 10−6) 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.

Alveolar soft part sarcoma in children and young adults: A report of 69 cases

Alveolar soft part sarcoma (ASPS) is a rare mesenchymal tumor characterized by ASPL‐TFE3 translocation. Apart from complete surgical resection, there is no standard management strategy.

Prevalence and predictors of overweight and obesity among a multiethnic population of pediatric acute lymphoblastic leukemia survivors: A cross-sectional assessment

As previous studies of obesity in survivors of pediatric acute lymphoblastic leukemia (ALL) have primarily been conducted among non-Hispanic white survivors or children treated on older protocols, our objective was to describe the prevalence and correlates of overweight status among an ethnically diverse population of pediatric ALL survivors, largely treated with more contemporary therapies. We evaluated the overweight/obesity status of pediatric ALL survivors (n=406) followed in the Texas Children’s Cancer Center between 2004 and 2014. Survivors were classified as underweight, normal weight, overweight, or obese on the basis of their body mass index at their most current follow-up visit. Our results showed that Hispanic ethnicity (39% of the subjects) was associated with being overweight (adjusted odds ratio=1.88; 95% confidence interval, 1.13-3.14) or obese (adjusted odds ratio=2.84; 95% confidence interval, 1.59-5.06) at follow-up, even after adjusting for cranial radiotherapy (CRT) exposure. Body mass index z-score at diagnosis was also associated with overweight/obesity at follow-up. In addition, there was a statistically significant interaction between younger age at diagnosis and CRT, indicating that younger age at diagnosis was associated with obesity among patients who received CRT. These findings may help identify pediatric ALL patients that are at increased risk of being overweight or obese after treatment.

Birth Characteristics and Childhood Leukemia Risk: Correlations With Genetic Markers.

Birth characteristics such as birth order, birth weight, birth defects, and Down syndrome showed some of the first risk associations with childhood leukemia. Examinations of correlations between birth characteristics and leukemia risk markers have been limited to birth weight–related genetic polymorphisms. We integrated information on nongenetic and genetic markers by evaluating the relationship of birth characteristics, genetic markers for childhood acute lymphoblastic leukemia (ALL) susceptibility, and ALL risk together. The multiethnic study consisted of cases with childhood ALL (n=161) and healthy controls (n=261). Birth characteristic data were collected through questionnaires, and genotyping was achieved by TaqMan SNP Genotyping Assays. We observed risk associations for birth weight over 4000 g (odds ratios [OR]=1.93; 95% confidence interval [CI], 1.16-3.19), birth length (OR=1.18 per inch; 95% CI, 1.01-1.38), and with gestational age (OR=1.10 per week; 95% CI, 1.00-1.21). Only the HFE tag single-nucleotide polymorphism (SNP) rs9366637 showed an inverse correlation with a birth characteristic, gestational age, with a gene-dosage effect (P=0.005), and in interaction with a transferrin receptor rs3817672 genotype (Pinteraction=0.05). This correlation translated into a strong association for rs9366637 with preterm birth (OR=5.0; 95% CI, 1.19-20.9). Our study provides evidence for the involvement of prenatal events in the development of childhood ALL. The inverse correlation of rs9366637 with gestational age has implications on the design of HFE association studies in birth weight and childhood conditions using full-term newborns as controls.

Abstract 5576: MnSOD polymorphism is associated with ototoxicity in pediatric medulloblastoma patients

Purpose: The SOD2 gene encodes manganese superoxide dismutase (MnSOD) and is critical for superoxide anion detoxification. Variants in SOD2 have been associated with noise-induced hearing loss, and animal models suggest MnSOD expression is up-regulated in the cochlea after treatment with platinum-based chemotherapeutic agents. Therefore, we examined the role of SOD2 variants on ototoxicity among cisplatin-treated childhood medulloblastoma patients. Methods: Peripheral blood samples were obtained from 100 patients treated for pediatric medulloblastoma or supratentorial primitive neuroectodermal tumor at Texas Children9s Cancer Center or MD Anderson Cancer Center between 1982 and 2009. Demographic, clinical, and treatment information was abstracted from patient medical records. A diagnosis of ototoxicity was assigned to patients whose medical records indicated they had received cisplatin chemotherapy and required the use of a hearing aid ≥1 year following the completion of primary therapy. DNA was genotyped on the Illumina HumanOmni-1 Quad BeadChip (San Diego, CA). A linkage disequilibrium-based single nucleotide polymorphism (SNP) selection strategy was used to identify a minimal set of informative common variants (minor allele frequency ≥5%). The association between each SNP and ototoxicity was assessed using multivariable logistic regression, assuming a log-additive model. Adjusted models included confounders (age at diagnosis, gender, craniospinal radiotherapy dose, cisplatin dose, amifostine therapy, and ethnicity) selected using a change in estimate approach. Results: Study participants were primarily male (73.2%) and non-Hispanic white (42.3%) with a mean age at diagnosis of 7.3 years. Of the 71 eligible patients with available information, 26 (36.6%) suffered from cisplatin-related ototoxicity. Five SOD2 variants (rs7855, rs5746151, rs5746136, rs2758331, rs4880) identified by the LD-based selection strategy were available in the genotyped data. After correcting for multiple comparisons, the C allele of the rs4880 variant was significantly associated with ototoxicity (OR = 3.00; 95% CI: 1.32-6.82) in adjusted models. Conclusions: In this study, the SOD2 rs4880 variant was associated with ototoxicity. The rs4880 T>C substitution results in a Val>Ala amino acid change at position 16 of the MnSOD mitochondrial targeting sequence. Specifically, 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. Characterizing genetic predictors of ototoxicity susceptibility may aid in prevention strategies and potentially identify novel antioxidant therapeutic targets. Citation Format: Austin L. Brown, Philip J. Lupo, Mehmet F. Okcu, Ching C. Lau, Surya P. Rednam, Michael E. Scheurer. MnSOD polymorphism is associated with ototoxicity in pediatric medulloblastoma patients. [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 5576. doi:10.1158/1538-7445.AM2015-5576