Publications by authors named "Mehmet F Okcu"

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.

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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).

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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.

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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.

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Background: We investigated whether surveillance imaging had an impact on post-relapse survival in patients with rhabdomyosarcoma (RMS). We hypothesized that relapse detected by imaging (group IM) would be associated with longer survival compared with relapse detected with a clinical sign or symptom (group SS).

Materials And Methods: We performed an observational multi-institutional study in 127 patients with relapsed RMS comparing overall survival (OS) after relapse using Kaplan-Meier and Cox proportional hazards analyses.

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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.

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Background: Endocrine deficiencies are common following Craniospinal irradiation (CSI) in children with brain tumors, but empirical data comparing outcomes following proton (PRT) and photon radiation therapy (XRT) are limited.

Methods: This retrospective chart review compared the incidence of hypothyroidism, Growth hormone deficiency (GHD), and Adrenal insufficiency (AI) in patients with medulloblastoma treated with XRT and PRT between 1997 and 2016. All patients received CSI and had routine endocrine screening labs to evaluate for thyroid dysfunction, GHD, and AI.

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Purpose: The majority of childhood cancer survivors do not follow-up for long-term risk-based screening for recurrent illness and treatment late effects, despite a high prevalence of secondary morbidities. The primary aim of this study was to investigate factors that influence long-term follow-up for survivorship care, from the perspectives of providers, patients, and caregivers.

Materials And Methods: A semistructured interview was designed to elicit stakeholder perspectives on factors that facilitate or impede routine clinic visits after completion of cancer therapy.

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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.

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Background: 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.

Procedure: The clinical data of 69 children and young adults less than 30 years old with ASPS diagnosed from 1980-2014 were retrospectively collected from four major institutions.

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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.

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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.

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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.

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Erratum to: Pediatr Cardiol DOI 10.1007/s00246-015-1203-8. The original version of this article unfortunately contained a mistake in the author’s group.

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Anthracycline chemotherapy (AC) is associated with impaired left ventricular (LV) systolic function. LV ejection fraction (EF %) obtained by two-dimensional echocardiography is the current gold standard for detection and monitoring of LV systolic function. However, dependence on LVEF has been shown to be unreliable due to its inherent limitations.

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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.

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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.

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Milk formula feeding can elevate insulin-like growth factor-1 levels, possibly impacting leukemogenesis. The intent of the current study is to examine the associations between infant feeding practices and age at introduction of solids on risk of childhood acute lymphoblastic leukemia (ALL). Incident cases of infant and childhood (aged ≤14 years) ALL (n = 142) were enrolled in a case-control study.

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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.

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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.

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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.

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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.

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Objective: To investigate the relationship between birth weight and risk of early age childhood cancer and whether racial differences in birth weight distribution could explain differences in the incidence of cancer in white, Hispanic, and black children.

Methods: We compared birth weights of 268 children younger than five years old and diagnosed with cancer in the State of Texas in 1995 to the birth weights of 2680 randomly selected, age-matched population-based controls. Birth weight, sex, race/ethnicity, maternal age, smoking status, parity, and gestational age information was ascertained from the birth certificates.

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